SAN FRANCISCO - Barry Bonds showed why Mets manager Willie Randolph chooses to walk the slugger so often.

Randolph faced constant questions Tuesday about whether it was still necessary to issue free passes to Bonds, considering his early season struggles.

Bonds then hit his 710th career home run, though Xavier Nady upstaged the San Francisco star with a tiebreaking solo homer to left over Bonds' outstretched glove in the seventh inning of New York's 4-1 victory over the Giants.

“I just want to say for all you second-guessers, that's why I walked Barry Bonds last night,” Randolph said. “He still has thunder in his bat. It's not like he can't be pitched to, but you have to respect how he can impact a game.”

Cliff Floyd splashed a Bonds-like two-run homer into McCovey Cove in the eighth for his second career homer into the water and the 12th by a San Francisco opponent. The Giants have done it 40 times - 31 by Bonds.

Floyd had been in a 4-for-24 slump on the Mets' current 10-game trip and was 0-for-7 in this series before hitting his second home run of the year.

“It was just awesome to contribute,” Floyd said. “It's been a tough month for me thus far but I'm going to take that positive and sleep better tonight.”

Steve Trachsel (2-1) pitched six strong innings and kept the Giants in check after allowing Bonds' second homer of the season and the slugger's first of the year at home, a drive starting the second.

David Wright and Kaz Matsui had two hits apiece for the Mets, who avoided their first three-game losing streak. Billy Wagner worked the ninth for his fifth save.

Bonds sent a 1-1 pitch from Trachsel into the left-field seats for his first homer in the Giants' waterfront ballpark since last Sept. 18 against the Dodgers - one of only two he hit at home last year in an injury-shortened season.

“It was nice,” Bonds said. “It felt good to hit the ball good today.”

The 41-year-old Bonds, nursing a tender surgically repaired right knee and a swollen left elbow, grimaced noticeably as he limped around the bases after his homer. He arrived at home plate to chants of “Barry! Barry!”

He returned to play left field in the top of the third, waving several times to the cheering fans before tipping his cap in two directions.

Bonds, who has said in recent days his knee is hurting, struck out on four pitches in the fourth, walked in the seventh and hit a game-ending flyout in the ninth.

He later complained that the Giants removed heaters from the dugout, forcing him to sit in the tunnel between innings wearing heat packs to keep his muscles warm.

“It's just sore. It was cold, real cold,” Bonds said. “We're used to having heaters in the dugout to keep yourself warm and loose and we don't have them. ... Sit in the tunnel with heat packs on is about all you can do.”

About an hour before the game he received a massage on his knee, which underwent three operations in 2005 and kept him out all but 14 games. He also briefly stopped his clubhouse card game in the afternoon to watch his television series.

Bonds, who hit his first homer of the year Saturday at Colorado, wasn't expected to be in the lineup for Wednesday's day game - the finale of the three-game series with New York.

“He had a great BP today,” Giants manager Felipe Alou said. “He's coming along.”

Trachsel, who allowed only two other hits, challenged the seven-time NL MVP and gave up his third career homer to Bonds, whose last seven homers at home have been solo shots. This one came a night after Bonds drew the 617th and 618th intentional walks of his career and went 0-for-1 with three walks in all.

Moises Alou drove in five runs following the intentional free passes in Monday's 6-2 win, giving the Giants 18 runs scored after Bonds' intentional walks this season.