CHICAGO -- Cubs pitcher Randy Wells threw two innings in an extended spring training game on Thursday in Mesa, Ariz., and the next step will be a Minor League rehab start for Class A Peoria, next Tuesday.

Wells has been sidelined with a strained right forearm since April 5.

Andrew Cashner, on the disabled list since April 6 with a strained right rotator cuff, threw two innings in live batting practice in Mesa. He was to throw on the side Friday and then the team would determine the next step in his rehab.

The Cubs' Double-A Tennessee team also announced Minor League outfielder Brett Jackson, the team's No. 1 Draft pick in 2009, was going on the disabled list with a strained ligament in his left little finger.

Davis 'ready to roll' for Cubs on Saturday

CHICAGO -- It was nearly a year ago that Doug Davis woke up early, sweating and feeling pain in his chest, jaw, neck and back. He tried taking heartburn medication, but that didn't help.

"I Googled what was going on, and it said signs of a heart attack," Davis said at the time.

He went to the hospital and was diagnosed on May 15, 2010, with pericarditis, an inflammation of the lining surrounding the heart. He had started five days earlier for the Brewers. Davis did eventually make another start July 9, 2010, but was then out the rest of the year because of left elbow problems, which required flexor tendon surgery.

On Saturday, Davis, 35, will make his first start in the Major Leagues since last July when he takes the mound for the Cubs against the Giants. The lefty signed a Minor League deal with the Cubs on April 12 and made one start for Class A Daytona on May 5, and one for Triple-A Iowa on Tuesday.

"He's ready to roll," Cubs pitching coach Mark Riggins said.

Davis stopped by the Cubs clubhouse early Friday to meet Riggins, manager Mike Quade and some of the players and staff. He will be officially added to the roster on Saturday. The Cubs do know the lefty. He beat them in the 2007 National League Division Series when he was pitching for Arizona. In his career against the Cubs, Davis is 9-8 with a 3.55 ERA in 18 games.

"I'm glad he's pitching for us," Quade said. "Every time he's taken the mound against clubs I've been around, it's been very bad for the clubs I've been on. He owned us in Oakland, and he was tough on us here in the playoffs with Arizona.

"He's an experienced guy, changes speeds, he's not going to overpower anybody, he's going to have to locate. Rarely do you get a guy with that kind of experience, is familiar with the opposition, and I think he'll handle all the rest of it very well."

Davis did have some butterflies Friday morning. Quade was happy to see that.

"It's exciting for him to be back in the game, and I think he's ready to go," Quade said.

Castro back at leadoff in fluctuating lineup

CHICAGO -- The only thing certain about Cubs manager Mike Quade is that nothing is certain.

"At this point, I think you guys should realize I'll do anything," Quade said in a discussion Friday about how he determines his lineup. "We don't have a set lineup. We have a set cleanup hitter, and that's it."

On Friday, Starlin Castro was back in the leadoff spot against Giants lefty Madison Bumgarner, and he went 3-for-5 with two RBIs and two runs scored in the Cubs' 11-4 win.

Castro has hit first, second, third, sixth and seventh. The only player who hasn't budged is third baseman Aramis Ramirez, who has batted fourth, but Quade said he's even thinking about moving him.

"It's a combination of what guys can handle, and nothing is off the table," Quade said. "I still think that given the guys in front of him who have been getting on base, he's in the right spot to drive in runs. If you move him, who slides into the four-hole to give you consistent RBI at-bats? I've thought about every combination -- I haven't had Castro ninth yet -- and nothing is ever off the table."

It's very doubtful Castro would bat ninth, even in an Interleague game. Ramirez, however, is 9-for-37 (.243) with runners in scoring position, and 0-for-13 with RISP with two outs.

Coleman working to establish consistency

CHICAGO -- All Casey Coleman needs is a little tweak of his mechanics and he should be fine, Cubs pitching coach Mark Riggins said Friday.

Coleman was roughed up Thursday by the Cardinals, giving up six runs on nine hits over 4 1/3 innings. He was able to get two key double plays to end the first and third innings, but a five-run second helped the Cards post a 9-1 victory.

"He had a really good game two games ago against Cincinnati," Riggins said. "[On Thursday], he got off a little bit mechanically. We worked on it today and it's a simple fix, and I think we can get him back on track."

Coleman, subbing for Randy Wells in the Cubs' rotation, seems to do better the more work he can get on the side.

"The more they throw off the mound, the better they get confidence," Riggins said. "[Saturday] will be a big day to get him back to where he was against Cincinnati. It's a minor thing and these guys get off, and it affects him."

Against the Reds on May 7, Coleman gave up two runs on four hits over six solid innings, striking out six. His next start will be against those same Reds, who will have had a chance to study video on the right-hander.

When Coleman (1-3, 7.22 ERA) has his command, he can be effective.

"But you've got to be consistent, and that's where he's lacking," Riggins said. "When he gives up the runs, he can't find it, and he has to find it quicker than that."

Extra bases

• Blake DeWitt was in the outfield on Thursday for the first time in his career, subbing in left. The infielder has been working out on his own for the last two weeks and Cubs manager Mike Quade suggested outfield coach Bobby Dernier work with DeWitt as well.

"He wants in, so why not?" Quade said. "He looks OK out there. It's not out of the question. Given the situation [Thursday, a 9-1 loss to the Cardinals], let's at least give him an inning to stand out there with the bleacher bums for an inning."

• Congratulations to Minor Leaguer Matt Szczur, who is taking an indefinite leave from Class A Peoria so he can take part in graduation ceremonies at Villanova.

• Saturday will be a rare night game at Wrigley Field. The last Saturday night game was Aug. 31, 2002, in the nightcap of a doubleheader against St. Louis (a 10-4 Cubs loss). The contest was a rescheduling of the June 22 game that was postponed because of the death of Cardinals pitcher Darryl Kile.

The last regularly scheduled Saturday night game at Wrigley Field was June 20, 1998, against the Phillies. Kerry Wood started that game, and got the win and hit his first home run. The Cubs have a clause in their contract that allows them to have Saturday night games if they are part of a national television broadcast. They will face the Giants on FOX.

• The Cubs' game against the Yankees on June 19 has been picked up by ESPN and will begin at 7:09 p.m. CT.