(Sports Network) - Randy Johnson isn't about to take it easy now that he has reached a career milestone. With the San Francisco Giants in need of a starter for tonight's finale with the Florida Marlins, the 45-year-old Big Unit takes the hill on three days' rest at Land Shark Stadium to wrap a four-game set.

A rainout on Wednesday versus Washington pushed back Johnson's last start to Thursday in the opener of a doubleheader. It was worth the wait for the towering lefty, as he held the Nationals to just an unearned run over six innings to become the 24th pitcher in major league history to reach 300 career wins.

Matt Cain then pitched the Giants to a win in the nightcap that day, but the doubleheader meant that either Johnson or Cain would have to pitch on three days' rest tonight, or San Francisco would have to bring up a starter from the minors.

The decision was made on Sunday night, as the 6-foot-10 Johnson will take the hill despite also suffering a bruised shoulder last time out.

"It validates Randy saying that it's not just 300 he's after," Giants manager Bruce Bochy said on the Giants' Web site. "He wants to help the organization and the team win ballgames. Here he is wanting the ball Monday after he could be pushed back a day or two."

Though just 5-4 with a 5.12 earned run average this year, Johnson is 2-0 over his last three starts and has a 1.04 ERA in that span. He is an excellent 8-1 with a 1.78 ERA in 13 games lifetime versus the Marlins.

It is unknown how long Johnson will be able to last tonight, so it is a good thing that Tim Lincecum gave the bullpen a bit of a breather in Sunday's contest. Lincecum fired 7 1/3 innings in guiding the Giants to a 3-2 victory while also improving to 5-0 over his last 10 starts.

Lincecum gave up three hits, including a two-run homer to Chris Coghlan in the eighth inning that made it a one-run game. Brian Wilson pitched a scoreless ninth inning to post his 15th save.

Bengie Molina drove in two runs for the Giants, who have won four of their last five and are 4-2 on a 10-game road trip that next takes the club back west to Arizona. Aaron Rowand had a pair of hits to stretch the majors' longest hitting streak to a career-high 17 games, a span in which he is hitting .411 (30- for-73) with three homers, 11 RBI and 12 runs scored.

The Marlins, meanwhile, fell to 4-3 on a season-long 11-game road trip that ends with a visit from St. Louis. Florida played without Jorge Cantu on Sunday due to dizziness. Cantu is scheduled to visit the doctors on Monday and his status for tonight is unknown.

The Marlins turn to their own tall left-hander in 6-foot-8 Sean West, who is still in search of his first career win. West did not factor into the decision of his first two big-league starts before getting a loss to Milwaukee on Wednesday. West allowed five runs (three earned) on four hits and three walks over 4 1/3 innings.

The 22-year-old has pitched to a 3.31 ERA over his first three starts.

San Francisco split its six matchups with the Marlins last season, but is 11-5 in the series since the start of the 2007 campaign.