CHICAGO -- Derrek Lee's swing was stronger than the gusty wind on a raw day at Wrigley Field.
"I guess we don't do anything the easy way," manager Dusty Baker said.
Lee's homer came on a 3-2 pitch from Heath Bell (0-1) and ended an 11-pitch at-bat. The Cubs, who won for only the third time in 11 games, took two of three from New York.
"He just kept challenging me. I'm glad we won. It was cold out there. I'm glad to get it over with," Lee said.
The gametime temperature of 49 degrees was 28 degrees colder than Tuesday night's game. Coupled with a 14 mph wind blowing in from left field, it had fans bundled up and players blowing on their hands all day.
But Lee, the Cubs' best hitter all season, got his drive through the wind and just into the seats in left-center.
"You couldn't get a cannon through that wind, and on the last pitch he was able to do it," Mets manager Willie Randolph said.
When the ball left Lee's bat, he wasn't sure it had enough.
"I had a lot of doubt when I hit it. I thought it was gone and as I was watching it I thought I was going to get mad, the ball isn't going to make it out," Lee said. "You saw a couple of balls hit that on normal days would be gone for sure."
Dempster blew his first save chance of the season, got the win and then went for X-rays on his right forearm after getting hit by Mike Piazza's line drive in the 10th. The X-rays were negative, and Dempster has a deep bruise. He will be evaluated Thursday.
With the Cubs leading 3-2 in the ninth, Dempster gave up a one-out walk to Doug Mientkiewicz and a single to David Wright before fanning Victor Diaz for the second out. But Valent lined a single to left to tie the game and deny Prior a victory.
It was the second start in a row that Prior pitched a gem, only to have his bullpen cost him a win by blowing a lead in the ninth. Chicago's struggling bullpen now has five blown saves.
The Cubs loaded the bases in the ninth, but couldn't score. Neifi Perez hit a comebacker to Bell, who started a 1-2-3 double play that ended the inning.
But Bell lost the showdown with Lee in the 10th. After the count reached 3-2, Lee hit five straight foul balls before connecting for the game-winner.
"Right now he's hitting the ball well and he hit it perfectly," Bell said. "It's not a good feeling. I had a pitch on the outside at 2-2 that I definitely thought was a strike. But you can't blame the umpire. I'm just more disappointed to let the team down."
Diaz's bases-loaded double in the second staked Victor Zambrano to a 2-0 lead, but Chicago scored three in the bottom half, taking the lead on Perez's RBI single.
Prior walked three and struck out seven, retiring 13 straight until Diaz singled with one out in the seventh. And the right-hander might have escaped the second inning if not for the first of two errors by second baseman Jerry Hairston.
Prior walked Cliff Floyd, and Hairston booted Piazza's potential double-play grounder before a walk to Mientkiewicz loaded the bases with none out. One out later, Diaz drove a two-run double off the right-field fence.
The Cubs scored three in the bottom half, thanks to Zambrano's wildness. Hairston was hit by a pitch, and Henry Blanco's fly into the wind fell in front of center fielder Carlos Beltran for a single. Zambrano committed a balk, then threw a wild pitch that allowed Hairston to score.
Prior walked, and when Corey Patterson hit a grounder to first, Mientkiewicz stepped on the bag and threw home, but Piazza couldn't hold it as Blanco scored, tying the game.
Perez then singled to score Prior for a 3-2 lead.
Zambrano allowed just three hits and three runs in six innings.
- Cubs 3B Aramis Ramirez missed the game with back spasms. He was forced to leave Tuesday night's game in the seventh inning when his back began to bother him and is day-to-day.
- Wright, who fouled a ball off his foot Monday and didn't play Tuesday, was back in the lineup with just a bruise. He made a diving stop of Lee's hard grounder in the fifth.
- Mientkiewicz saved a run in the fourth when he went high in the air and knocked down Patterson's line drive, picked up the ball and beat him to the bag.
- Prior threw 110 pitches.