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9/7/2013 3:40 A.M. ET

Fowler leaves game after aggravating knee

SAN DIEGO -- Rockies center fielder Dexter Fowler aggravated the left knee injury that cost him six games last week, and he had to be removed from Friday night's 4-3 loss to the Padres before the bottom of the sixth inning.

The injury occurred in the fifth, when Fowler stole second base -- his 19th steal this season. His left knee hit the bag, then slammed into his right foot and ankle. Rockies head athletic trainer Keith Dugger tended to Fowler on the field, and he finished the inning and played the bottom of the fifth on the field.

It was Fowler's third game back from sitting out with a twisted left knee. The removal from Friday's game continues a difficult, injury-filled season for Fowler, who was hitting .302 with a .399 on-base percentage as of June 13, the day he was hit on the right hand by a pitch. Fowler played with the injury briefly, then went on the disabled list and missed 14 games.

Playing through his various injuries, Fowler is batting.262, but with a still-healthy .369 on-base percentage. He went 1-for-2 with his 18th double of the season, a walk and a run on Friday.

Rockies to pitch Oswalt this weekend

SAN DIEGO -- The Rockies activated veteran right-hander Roy Oswalt on Friday and will use him on Sunday in tandem with right-handed rookie Chad Bettis.

Oswalt has not pitched in the Majors since July 7, when he strained his left hamstring. He also suffered a setback during rehab. But coming off a strong rehab outing for Rookie level Grand Junction on Tuesday (no runs, three hits in 5 2/3 innings), Oswalt, 36, is ready to return. Bettis (0-3, 5.45 ERA in seven starts) will start on Sunday and Oswalt will follow. After that, the Rockies will work Oswalt into the starting rotation as the team formulates its plans for 2014.

"I'm going to piggy-back him behind Bettis on Sunday," Rockies manager Walt Weiss said. "We're trying to build Roy back up to make a few starts before the end of the season.

"I'd like to get a good look at him before the end of the season. We feel like he could help us. He's missed a lot of time, but we still like him enough to watch him pitch the rest of the year."

The Rockies would like to go into Spring Training with an experienced pitcher or two competing for rotation spots. This year, the Rockies signed lefty Jeff Francis during the winter and righty Jon Garland just before the start of the season, although neither made it to midseason in the rotation.

Oswalt, a three-time All-Star, has expressed interest in returning to Colorado next season and believes he will be healthy and effective. Oswalt was 0-4 in four starts with a 7.56 ERA before the injury.

"I actually feel pretty good," Oswalt said. "I'll have to get out there and pitch to know for sure, but my arm feels great. It felt great the other night in Grand Junction. The thing is it wasn't a pitcher-type injury; you don't see too many pitchers have a hamstring problem from pitching. It was a freak play [covering home plate on a wild pitch].

"If I was having chronic back issues or arm issues, I'd probably think differently. But right now the body feels great. I'll see where I'm at after these starts, but I believe I'll feel good enough to play next year."

By working Oswalt into the rotation, the Rockies can limit the workload of Bettis, 24, who missed last season because of a shoulder injury that didn't require surgery. Bettis has thrown a combined 97 2/3 innings this season between the Majors and Double-A Tulsa.

The Rockies also activated left-hander Drew Pomeranz, who hasn't pitched since July 21 because of left biceps tendinitis. However, Weiss said Pomeranz is not ready for game action.

Arenado doesn't start due to right thumb bruise

SAN DIEGO -- Rockies third baseman Nolan Arenado, a prime candidate to win the National League Gold Glove Award as a rookie, was out of the starting lineup on Friday night because of the right thumb bruise he suffered in Wednesday night's 7-5 victory over the Dodgers. But he insists the injury will not cost him any more time.

Even if his thumb hurts, Arenado, 22, has reason to fight through the pain.

"My body feels good, my mind feels good, and I have the most games played on the team and my goal is to finish with the most," said Arenado, whose 116 games going into Friday's game against the Padres put him two games ahead of catcher Wilin Rosario and right fielder Michael Cuddyer, who were in the lineup. "That would be pretty special for me.

"I want to finish strong, and I want to play in every game after today."

Arenado wasn't called up to the Majors until April 28, and he has sat rarely since. The fact he's leading the team in games is partly due to his youth and durability, but also partly to the fact that several regulars have spent time on the disabled list.

In addition to the highlight-reel defense, Areando has accounted well for himself at the plate, hitting .271 with 10 home runs and 47 RBIs. Manager Walt Weiss kept him in the lineup despite some periods when pitchers took advantage of his inexperience, and it's beginning to pay off in positive numbers.

Arenado entered Friday's 4-3 loss to the Padres as a defensive replacement in the ninth inning, and Jesus Guzman's walk-off single scooted just fair beyond his reach to end the game.

Torrealba switches to heavier mask

DENVER -- Rockies catcher Yorvit Torrealba has looked a little different behind the plate since his return from the concussion that cost him eight games last month.

Rockies head athletic trainer Keith Dugger convinced Torrealba not to wear his state-of-the-art mask with silver titanium bars and lightweight padding. Instead, he is wearing one of fellow catcher Wilin Rosario's masks -- with the company logo covered, since Torrealba has an equipment deal with another company. The purple bars are old-fashioned steel, and the padding is heavier.

Dugger and Torrealba are operating under a theory that the titanium mask might have been too strong and too light. The bars are so strong, the theory goes, that there is no give, which means all the impact is transferred to the catcher's face, and the padding isn't enough to cushion the catcher's face.

There was a recent run of head trauma injuries to catchers, many occurring as Torrealba's did, on a foul tip. The St. Paul Pioneer Press reported this week that Twins catcher Joe Mauer and Ryan Doumit were wearing titanium masks when they suffered concussions, and at least three other injured catchers were wearing the material. Torrealba was one of them.

Torrealba said it will take some time to get used to the old-time mask.

"Honestly, I don't really know," Torrealba said. "The titanium, I like it. It's light and I see a lot of players using it. But I might be one of the cases where the mask was too strong. But I don't know that."

Dugger said some of the steel masks would bend on dramatic impact. Not only could the bending help cushion the blow, it could be a warning that the bars are worn and must be changed. Titanium, he said, doesn't show wear that way. It just breaks eventually.

Neither Torrealba nor Rosario wear the hockey-style mask that many catchers wear -- one that's required at the high school level. Both catchers and Dugger like the idea of the stand-alone mask over a helmet, because the mask usually shakes loose from the skull at impact. But in Torrealba's case, the mask stayed put, which made the blow more blunt.

"Yes, the titanium can take more force, but that force has to be transferred somewhere else," Dugger said. "I'm not saying it's bad. I'm sure they have tests that show it's safer and better. What I'm saying is based on observation, not 100 perent science.

"But even some of the older umpires, they feel like the force is a little stronger because there's no give. But I will say one thing: Those titanium masks last longer."

Cuddyer enjoying race for NL batting title

SAN DIEGO -- Rockies veteran Michael Cuddyer fashioned a 27-game hitting steak earlier this season, partly because he didn't allow the weight and attention to affect him. He was not one of those players who shied away at talk of the streak out of superstition, and he generally had fun with it.

Cuddyer said he is taking the same attitude toward his push for the National League batting crown. Cuddyer is hitting .329 -- one point behind the Braves' Chris Johnson -- after he went 0-for-3 with an RBI groundout in Friday's 4-3 loss to the Padres.

"I just take it as it comes," Cuddyer said. "I'm not focused on having to go 2-for-3, 3-for-4. I want to try and execute when I step in the batter's box.

"I'm very happy with the way I've been able to be consistent. Your goal as a player is to give your team a chance, give a solid effort, regardless of the numbers. I've given full effort every day."

Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, and follow him on Twitter @harding_at_mlb. This story was not subject to the approval of Major League Baseball or its clubs.