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5/1/2014 3:05 A.M. ET

Chacin on track to replace Chatwood in rotation

PHOENIX -- The Rockies are not ready to name a replacement for Tyler Chatwood in the starting rotation, but Jhoulys Chacin appears to be the top option.

Chacin, who has recovered from a strained right shoulder, completed his rehab assignment and appears on track to return to the big leagues Sunday against the Mets. Chacin allowed one run on four hits in six innings in a rehab start for Triple-A Colorado Springs on Tuesday against Memphis.

"It's hard to say because we are several days away, but it looks like the natural fit," Rockies manager Walt Weiss said. "Jhoulys has to be re-evaluated, too. He just made a start, and he's going to have to throw a side and go through the routine that he has in between starts and make sure that he's OK."

Chacin went 1-1 with a 2.53 ERA in 10 2/3 innings over two games at Triple-A. He also pitched two games for Class A Advanced Modesto during his rehab stint.

"It's difficult to think four or five days ahead in this game because things chance on a daily basis," Weiss said.

Elbow strain sends Chatwood to DL; Bettis recalled

PHOENIX -- The Rockies placed right-hander Tyler Chatwood on the 15-day disabled list with a right elbow strain Wednesday afternoon.

Chatwood was removed from Tuesday night's game at Chase Field with the bases loaded and none out in the sixth inning because of tightness in the elbow. The club is waiting on the results of Wednesday morning's MRI.

"It was real tight under my flexor tendon, and in the sixth inning, in my warm-up pitches, I could barely get the ball to home plate," Chatwood said. "So I should have known then, but I tried to go through it and wasn't able to control the ball or anything."

In the eventful sixth, Chatwood walked Aaron Hill, gave up single to Eric Chavez and walked A.J. Pollock to load the bases. Rockies trainers and manager Walt Weiss went to the mound and removed Chatwood in favor of right-hander Chris Martin after throwing ball one to Chris Owings.

"It was nothing more than normal soreness, it just got worse as the game went on last night," Chatwood said.

The club recalled right-hander Chad Bettis from Triple-A Colorado Springs to take Chatwood's place on the roster. Bettis was on the Opening Day roster and went 0-1 with a 7.15 ERA in 11 games before he was optioned to Triple-A on April 25.

"It's a shame something like that happened to [Chatwood], and it's something you never wish on anybody," Bettis said. "But that's where we're at right now. It's good to be back, but you never want to see one of your guys go down."

Chatwood, who is 1-0 with a 4.50 ERA this year, was placed on the disabled list earlier this season because of a strained left hamstring suffered while running the bases during the final Spring Training game in Arizona.

"I'm concerned about him," Weiss said. "Anytime a pitcher has to come out of a game because of an elbow, it's a concern. His elbow is tight and it was obvious that he was not going to be able to make his next start."

Worth noting

• Catcher Wilin Rosario (contusion on left hand) took batting practice Wednesday afternoon and continues to make improvement. He's been out of the lineup since Saturday.

"It was a good day for Wilin. We got a good report," manager Walt Weiss said. "I think a lot of improvement from yesterday."

Rosario is hitting .244 with three home runs and 13 RBIs in 22 games this season. He injured the hand against the Dodgers last weekend.

Nolan Arenado went 1-for-4 Wednesday night against the D-backs to extend his hitting streak to 20 games, with six doubles, two home runs, eight RBIs and 11 runs scored during that stretch.

• Troy Tulowitzki has 22 career home runs against the D-backs, his most against any team in the Major Leagues.

Jesse Sanchez is a national reporter for MLB.com. Follow him on Twitter @JesseSanchezMLB. This story was not subject to the approval of Major League Baseball or its clubs.