DENVER -- Jeremy Guthrie will get another chance to prove he belongs in Colorado's rotation on Sunday.

"He's going to take the start in Detroit," said manager Jim Tracy. "I think he's well aware of the fact that we need to begin to see some significant improvement."

The struggles of the Rockies' starting pitchers, beleaguered owners of an MLB-worst 6.27 ERA, have been well documented, but Guthrie has perhaps had the roughest go of it recently. He served a 15-day stint on the disabled list from April 23-May 15 after falling off his bicycle and injuring his wrist, and has not looked sharp since.

As bad as Tuesday night's start was against Oakland -- in which he gave up seven earned runs, including six in the third inning -- it was the first start in four tries in which Guthrie did not give up double-digit hits. When asked after the 8-5 loss if he'd benefit from skipping a start, Guthrie made it clear he didn't think he would.

"I don't need that," said Guthrie, who leads the National League in home runs yielded with 15. "I feel fine physically."

Guthrie is 2-2 on the road with a 4.23 ERA, compared to 1-3 with a 9.53 ERA at home. In Detroit, he'll face a tall task against an offense that ranks fourth in the American League in hitting. He should, however, benefit from playing in a ballpark that is much more pitcher-friendly. Coors Field has seen 28 multi-homer games this year; Comerica Park has 19.

"[Coors] is different, that's all I can say. It's no excuse, everybody has to throw here too," Guthrie said Tuesday night. "It's very different than what I've experienced. The effect it's has on some of my pitches has been more than I've expected. It's part of the equation, not something I'd use as a crutch."

In 21 1/3 innings pitched at Comerica Field, Guthrie has a 2.95 ERA, with two home runs allowed. In his 53 career innings pitched against the Tigers, Guthrie has a .257 opponent batting average.

The Tigers' Miguel Cabrera has a .357 batting average against Guthrie in 14 at-bats, with two of his five hits being homers. Guthrie has never faced Prince Fielder. If Guthrie fails to go five innings or gives up five or more runs, it's likely the Rockies would be pressed to make a change.

"We're not talking about the leash being from [first-base dugout] to the other dugout, we need to start seeing some results, some consistency," Tracy said.

Colvin in left field as CarGo gets day off

DENVER -- Rockies manager Jim Tracy realizes it'd be unfair to keep Tyler Colvin out of the Rockies lineup in the midst of a scorching stretch, so he's finding creative ways to continue giving him opportunities.

Usual left fielder Carlos Gonzalez took a scheduled day off Wednesday against Oakland for rest -- his fourth this year -- so Colvin manned left, Dexter Fowler resumed his usual post in center field after coming off the bench the previous two games and Michael Cuddyer stayed in right field. With Thursday being a day game, Tracy hinted Todd Helton could take a day off and either Colvin or Cuddyer could play first, with the other playing right field.

"Tyler is showing signs of being an even better player than he was in 2010 when he hit 20 home runs with the Cubs," Tracy said. "There isn't any place you can put him defensively where he doesn't look smooth; he's very graceful."

In three starts, two against the Angels and one against the A's Tuesday night, Colvin is batting .700 with four homers and six RBIs and has drawn three walks. His 20 total bases since June 9 are the most in the Majors -- and the Rockies didn't have a game on Monday.

Injury report: De La Rosa not throwing yet

DENVER -- Rockies pitcher Jorge De La Rosa is still on his road to recovery from Tommy John surgery on his left elbow, which he underwent last June. "He's not doing any throwing right now, just being treated," said Rockies manager Jim Tracy.

De La Rosa has had his rehab assignments halted twice and has not pitched in a game since May 10 of last season. His injury has been a huge blow to a starting rotation that has struggled to find its footing, as he won 16 games in 2009.

In other injury news:

• Right-hander Jhoulys Chacin is continuing to progress and is now playing catch on flat ground, Tracy said. Chacin was optioned to Triple-A Colorado Springs -- after going 0-3 with a 7.30 ERA in five starts -- before the Rockies rescinded the move and instead placed him on the 15-day disabled list with inflammation in his right shoulder. Chacin had sub-4.00 ERAs in 2010 and '11.

• Right-hander Juan Nicasio, placed on the 15-day disabled list June 3, has full range of motion back in his left knee. Nicasio (2-3, 5.28 ERA) is on track to do some light tossing in a couple of days.

• Catcher Ramon Hernandez currently is not participating in any baseball activity. Hernandez was added to the 15-day disabled list May 24 with a left hand strain.

• Utility infielder Jonathan Herrera's hamstring is fine but he has experienced some soreness in his right shoulder. After an MRI, the Rockies determined nothing is structurally wrong with the shoulder. Herrera went on the 15-day disabled list May 22 with a strained right hamstring.