"Randy Johnson's pursuit of career win No. 300 will have to wait another day.

The San Francisco Giants left-hander was due to start Wednesday night against the Washington Nationals in his first attempt at joining the most exclusive pitching club in baseball, but several lines of vicious thunderstorms and a soaked field forced the game to be postponed after a delay of more than 3 1/2 hours.

"We really tried," Nationals president Stan Kasten said. "The umpires did a great job. We were all trying to get it done. But at the end of the night, it's not worth the risk to our players to play on that field tonight."

The two teams now will play a true doubleheader Thursday beginning at 4:35 p.m. Johnson will start the opener against Nationals rookie Jordan Zimmermann, with Matt Cain facing Ross Detwiler in the nightcap.

Fans who held tickets to Wednesday's game can exchange them for any comparable available seat at a future game this season excluding the June 23-25 interleague series against the Boston Red Sox.

A larger-than-normal crowd - not to mention a sizable media contingent - had gathered at Nationals Park to witness Johnson attempt to become the 24th pitcher in baseball history to win 300 games. But the Big Unit never emerged from the visiting clubhouse to begin pregame warmups.

Afternoon showers canceled batting practice, and the tarp remained on the infield as a strong line of storms hit the area shortly before the scheduled 7:05 p.m. first pitch., flooding much of shallow right field. The grounds crew pulled the tarp at about 8 p.m. and drained the outfield, only to have to cover the infield again as another line of storms approached.

Kasten had remained hopeful of getting the game in but conceded the field had taken on too much water after examining shallow left field with the entire umpiring crew.

"It was pretty bad," Giants manager Bruce Bochy said. "They did all they could. We wanted to get it in, but we dont want to make it a farce."

Zimmermann, who made his big league debut April 20 after a 2-hour, 10-minute rain delay, said once it became obvious the field was soaked, he preferred to wait till Thursday to take the mound. "