PITTSBURGH -- More than three hours after the scheduled first pitch, the Pirates' series finale against the Cubs was called on Wednesday after a lengthy thunderstorm had left too much water on the PNC Park warning track.

The storm, which included a brief tornado warning and nearly two hours of excessive lightning, had stopped well before the game was called. However, there was so much water gathered on the warning track that both teams agreed the field was not suitable for play. More rain was expected to arrive in Pittsburgh later in the evening, too.

The Pirates' grounds crew spent over an hour trying to squeegee the water off the warning track before the final call was made. By that time, members of both organizations -- including managers John Russell and Lou Piniella, Pirates president Frank Coonelly and general manager of PNC Park Dennis DePra -- had huddled together in center field after evaluating the outfield conditions.

"It's a shame," Russell said. "The grounds crew worked really hard. It was still a mess, and I think the biggest thing was more rain is coming. That was the biggest thing that shut us down."

The call to postpone the game officially came at 10:17 p.m. ET. The game was rescheduled for Monday at 12:35 p.m. ET. The Pirates have the day off before heading to Washington, while the Cubs had Monday as an open date in between series in Houston and Milwaukee.

Zach Duke, who was scheduled to start for the Pirates on Wednesday, will now go against the Giants on Friday. What this means, though, is that the left-hander will not be able to face Stephen Strasburg, as scheduled, when Strasburg makes his Major League debut Tuesday.

Paul Maholm and Ross Ohlendorf will follow Duke in this weekend's series against San Francisco. Russell did not announce a starter for Tuesday's game against the Nationals, though Jeff Karstens, Dana Eveland or Brian Burres might be the only available options.

The Pirates entered the night eyeing their second sweep of the Cubs this season. Pittsburgh had taken the first two games of this three-game set by a combined two runs to move to 7-1 against Chicago this season. This was scheduled to be the Cubs' final visit to PNC Park this season.

Fans holding tickets to Wednesday's postponed game can use those tickets for the makeup game or can exchange them for any remaining home game during the 2010 season except Skyblast dates. Exchanges can be made at the PNC Park Ticket Office or by mailing the unused tickets to: Pittsburgh Pirates Ticket Office, P.O. Box 7000, Pittsburgh, Pa., 15212.