CHICAGO -- There is one thing that Andy Sonnanstine knows for sure as he prepares to take the mound for the Rays in Game 4 of the American League Division Series against the White Sox on Monday.

"It is the biggest game of my life," Sonnanstine said.

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Tampa Bay hasn't slipped into a must-win situation just yet, but the club is gearing up for its second shot at clinching the first postseason series victory in franchise history. The Rays had that opportunity on Sunday, but dropped a 5-3 decision to the White Sox at U.S. Cellular Field.

The Rays still hold a 2-1 series edge, but the club wants nothing more than to end the wait in Chicago. With that in mind, Tampa Bay turns to Sonnanstine, who has gone from possibly being excluded from the playoff roster to the pitcher the team is handing the ball with a trip to the AL Championship Series hanging in the balance.

Sonnanstine believes he's up for the challenge.

"One of the big things for me is to stay calm," Sonnanstine said, "and keep an even keel throughout the season and into the postseason. I think I'll be ready. I don't think I'll be that nervous."

Chicago's fans will try to disrupt Sonnanstine as much as possible. On Sunday, the crowd banded together in wearing black and violently waving white towels to help the White Sox utilize home-field advantage.

Sonnanstine expects to receive the same treatment.

"This is a hostile environment we're going to be coming in to," he said. "I do a pretty good job of getting locked in."

Sonnanstine paused and smiled.

"Hopefully, I can not get disrupted by the towels."

The Rays are probably hoping Sonnanstine can simply get his season back on track.

The 25-year-old right-hander edged out Edwin Jackson for the fourth rotation spot on the playoff roster, but endured a significant slump to end the regular season. Over his final seven outings, Sonnanstine went winless, posting an 0-3 record with a 4.39 ERA. He had gone 3-0 with a 2.92 ERA in his previous four starts.

Game 4: Just the facts
U.S. Cellular Field
Rays starter: RHP Andy Sonnanstine
2008: 13-9, 4.38 ERA
2008 on road: 6-5, 4.35 ERA
2008 vs. White Sox: 1-0, 3.00 ERA (3 appearances)
Career vs. White Sox: 1-0, 2.96 ERA (4 appearances)
Career postseason: First appearance
White Sox starter: RHP Gavin Floyd
2008: 17-8, 3.84 ERA
2008 at home: 10-3, 3.55 ERA
2008 vs. Rays: First appearance
Career vs. Rays: First appearance
Career postseason: First appearance
Rays lead series, 2-1. The White Sox are the 12th team to win Game 3 after losing the first two games of a Division Series.
Game 1: Rays 6, White Sox 4
Game 2: Rays 6, White Sox 2
Game 3: White Sox 5, Rays 3
Did You Know? The White Sox went just 9-31 in regular-season games this year when they didn't hit a home run. All their RBIs in Sunday's victory came on singles and sacrifice flies.
Sonnanstine made Tampa Bay's playoff roster due to his reputation as a reliable strike-thrower, though.

In his 32 starts, Sonnanstine threw 67 percent of his pitches for strikes, had a 3.35 strikeout-to-walk ratio and averaged 15.1 pitches per inning. Jackson finished with 14 wins to Sonnanstine's 13 this year, but he threw 61 percent strikes, owned a 1.40 strikeout-to-walk rate and averaged 16.7 pitchers per frame.

Basically, the key for Sonnanstine against the White Sox will be pounding the strike zone.

"He just needs to pitch the same way that he's been pitching the whole season," Rays catcher Dioner Navarro said. "There's nothing different that he has to do. Just pitch his game and try to locate his pitches, just the way that he's been doing through the whole season."

Helping matters is the fact that Sonnanstine had some success against Chicago this year.

On April 19, Sonnanstine spun a complete-game shutout at home against the White Sox, scattering three hits in the win. The starter took no-decisions against Chicago on both June 1 and Aug. 24, posting a 5.25 ERA in those two outings. Overall, Sonnanstine is 1-0 with a 2.96 ERA in four career starts against the Sox.

"I've been watching them all year and doing my homework," said Sonnanstine, who went 13-9 with a 4.38 ERA this season. "It's a dangerous offense. That's a good quality team -- most teams in the postseason are."

One more win, though, and the Rays can put the White Sox in the rearview mirror.

"We feel pretty confident," Sonnanstine said. "We're still up one game on them. I think we're going to come out and play our game tomorrow. I like our odds."