Willis pitched seven strong innings to become the first 11-game winner in the majors, leading the Florida Marlins to a 9-1 victory over the Cubs on Monday night.
"I'm just having fun and playing the game the way I know how to play," Willis said.
Willis gave up one run and seven hits, struck out five and walked none. He also had two hits and drove in a run in the fifth, when the Marlins broke open the game with seven runs.
"He's the stopper, the savior and everything else," Marlins manager Jack McKeon said. "I don't care whether we start him or DH him."
Miguel Cabrera, Paul Lo Duca and Alex Gonzalez each drove in two runs for the Marlins, who won for the third time in four games after losing eight of 10. Luis Castillo hit his first homer of the season in the ninth.
Willis (11-2) won his third consecutive start as the Marlins opened a 12-game, four-city road trip, their longest of the season.
"It was a big game for us today, starting off the road trip," Willis said. "We came ready to play."
Willis beat the team that drafted him for the first time in four career starts. He has already surpassed his win total from last season, when he went 10-11.
"He's definitely gotten a lot better since the last time I faced him," said catcher Michael Barrett, who went 0-for-3 against Willis. "Today he mixed up speeds more than anything else. I think that's what kept us frustrated and unable to get any runs today."
John Koronka (1-2) gave up six runs and seven hits with three walks in 4 1/3 innings.
After Willis singled in the fifth, Juan Pierre beat out a double-play grounder and Castillo singled past a diving Derrek Lee at first base to put runners on first and third. Cabrera and Carlos Delgado each followed with run-scoring singles for a 3-1 lead.
Barrett said Willis' leadoff single was the turning point in the game, because it brought up the speedy Pierre with a man on base.
"To be able to get some knocks and put (Koronka) in a hard situation, that's good," Willis said.
After a meeting with pitching coach Larry Rothschild, Koronka walked Mike Lowell to load the bases, ending his third start of the season. Koronka has given up 13 runs and 19 hits in 15 1/3 innings since getting called up from Triple-A Iowa.
"We have to go back to the drawing board and see what our options are, including him," Cubs manager Dusty Baker said. "He threw the ball better tonight early than he had in his last couple starts."
Former closer Joe Borowski entered and gave up a pair of two-run doubles to Lo Duca and Gonzalez and a run-scoring single to Willis. Borowski was booed leaving the field after getting Pierre to bounce into a force to end the inning.
"We put together some good at-bats in that inning," Delgado said. "You want to take advantage of situations like that."
The Marlins took a 1-0 lead in the third. Pierre led off with an infield single, took second on Koronka's balk and stole third. He scored two batters later on Cabrera's RBI groundout.
Lee and Aramis Ramirez tied it in the fourth with consecutive doubles off Willis. Willis struck out Jeromy Burnitz and Corey Patterson to end the inning and gave up just two hits after that.
- Lowell jammed his ankle sliding into third base in the fourth inning. "It looks like he'll be OK tomorrow," McKeon said.
- Al Leiter (2-6, 6.75 ERA) is moving to the bullpen for now as the Marlins will temporarily go with four starters with two off days in the next week. Leiter hasn't pitched out of the bullpen since 1993 with Toronto.
- It was the second time this season the Cubs have given up seven runs in an inning. The other came on May 1 at Houston in the fifth inning.
- This was the first meeting of the season for the teams, who built a rivalry when the Marlins won the 2003 NL Championship Series in seven games en route to the World Series title.
- Cubs pitcher Kerry Wood gave up one run in three innings in his first rehab start at Triple-A Iowa on Monday. He struck out three and walked two, throwing 46 pitches. He also tripled and scored.