TAMPA, Fla. -- Joba Chamberlain will roll out of bed on Wednesday morning knowing he may be running out of time to prove himself as the Yankees' best candidate for the fifth-starter job.

Heading into his third Grapefruit League outing (Andy Pettitte will start), this one against the Phillies in Clearwater, Fla., at 1:05 p.m. ET on MLB.TV, Chamberlain has been informed that the Yankees need to see more if they are to take the right-hander's bid seriously.

"You've got to pick it up," Yankees manager Joe Girardi said. "We've told him that you've got to pitch now. We gave you those first couple of starts to get under your belt, and now you've got to show us. You've got to pitch."

Chamberlain, 24, came into the spring challenging a field of candidates that included Phil Hughes, Alfredo Aceves, Chad Gaudin and Sergio Mitre to round out New York's starting five. Thus far, Chamberlain's results have been at the back of the pack, compiling a 27.00 ERA over 3 2/3 spring innings.

He allowed six runs on March 10 against the Tigers, and said after the start that he understands the clock is ticking.

"There's no panic button, but sure, there's definitely a sense of urgency," Chamberlain said. "It matters every time I go out how I do, but I'm going to take every negative and turn it into a positive. But I can't worry about what anybody else did. I have to worry about getting better and concentrating on what I have to do well to help the team."

Each of the five candidates will receive at least one more start in Grapefruit League play, and Chamberlain will have a tough act to follow after Hughes pitched four innings of scoreless three-hit ball in the Yanks' 4-1 win against the Astros on Tuesday, lowering his spring ERA to 2.08 through 8 2/3 spring frames.

Girardi said that Hughes attacked the strike zone with a good curveball, but Hughes seemed most pleased with his changeup, which he threw in counts where he wouldn't usually use it -- 2-1, for example -- and got good results, letting his fielders do the work.

"It's one thing to try to throw fastball, curveball, cutter and get out of every inning 1-2-3, but at the same time, I want to have results this year based on my changeup," Hughes said. "I think the only time to really get that work in is in games. You can throw them in the bullpen all year long, but it's really not the same."

Hughes' work in relief last season was a major reason why the Yankees' bullpen was a major strength heading toward the postseason, but he acknowledged on Tuesday that it may be beneficial for his long-term career if he can win this job outright.

"Development-wise, it would do a great deal," Hughes said. "I'd be able to go and throw those four pitches every five days, and get more innings if I am starting. Development-wise, it would do a lot for me, but it basically comes down to what the team wants. It's not my place to go around that at all."

Also in the mix, Aceves has been arguably the sharpest, with an 0.90 mark through 10 frames. Gaudin (7.71 ERA in seven innings) and Mitre (3.00 ERA in nine innings) also remain under consideration.

"I think overall the guys have thrown the ball pretty well, for the most part," Girardi said.

The Yankees will send Chamberlain to the mound on Wednesday eyeing four innings or 60 pitches, hoping he can improve at pitching inside with his fastball, as well as increase his stamina going through the effort.

"You want to see him execute pitches," Girardi said. "Do the things that you have to do to be successful. Be ahead in the count, you don't want to be walking people. You want to attack hitters and you want to make quality pitches."

Girardi said that he was happy to see Chamberlain's velocity get up to 94 mph in the start against Detroit and thought he threw good sliders. But his inability to get fastballs in on right-handed hitters is a concern.

"I asked him to work on some things, and he didn't execute those things that he was working on," Girardi said. "I think it made his line a lot worse. But we know that we need to work on those things."

Girardi has talked about using March 25 or 26 as the target date for a decision, so the pitchers who are going to be in the bullpen can get used to having to warm up more quickly. But that is not a hard-and-fast date in the event they need more time to settle the final verdict.

"There are no rules here," Girardi said. "We'll just do it as we feel is necessary."