Stephen Strasburg (back strain) scratched; Nats don't think injury is serious

Sutcliffe: Strasburg not ducking start against Kershaw (1:00)

Dave Flemming and Rick Sutcliffe offer their takes on Stephen Strasburg being scratched from his start against Clayton Kershaw and the Dodgers. (1:00)

LOS ANGELES -- A marquee pitching matchup in Los Angeles fizzled Monday evening when the Washington Nationals scratched Stephen Strasburg from his scheduled start with an upper-back strain.

Strasburg was supposed to start opposite the Los Angeles Dodgers' Clayton Kershaw, which would have made it the first pairing ever between the two staff aces.

Nationals manager Dusty Baker told reporters after Washington's 4-1 loss that the team doesn't think Strasburg's injury is serious and that he is hopeful the right-hander will make his next start in six days.

"We were looking forward to seeing [the matchup] also," Baker said. "But we've got to do what's best for the ballclub and [Strasburg]."

Strasburg pitched just 127 innings last season due to various injuries but had been healthy this year.

Baker said Strasburg was injured while working out "pretty vigorously" on his off day and not while pitching.

"It was something to do [with] his rib cage," Baker said.

"We found out, we had an idea yesterday. But our trainers were working on him. They worked on him all day yesterday, and they worked on him today. We were even thinking about it at 5 o'clock, but he still felt it in there, so we thought it was best he doesn't pitch. Because we've got a long way to go."

Strasburg is 10-0 over his first 14 starts of the season with a 2.90 ERA, slightly under his career mark of 3.07. He is 1-0 with a 1.71 ERA in four career starts against the Dodgers, striking out 25 in 26⅓ innings.

Entering Monday, Kershaw was 9-2 with a 2.09 ERA in 13 games (12 starts) against Washington. He continued his strong showings against the Nats by allowing six hits and one earned run in seven innings Monday with eight strikeouts and no walks. He now has won eight consecutive starts against the Nationals and has allowed two runs over his past five starts (38 innings) against them.

In place of Strasburg, the Nationals handed the ball to right-hander Yusmeiro Petit, who had posted a 2.81 ERA over 17 relief appearances this season. It was just Petit's second start over the past two seasons, and he gave up five hits and three runs (two home runs) over six innings. He also struck out five and walked one.

The Strasburg-Kershaw matchup would have been just the second in baseball history between pitchers with double-digit victories and fewer than two defeats. And if the past was any indication, there would have been some drama.

In 1900, the Dodgers' Joe McGinnity and the Phillies' Bill Bernhard met when each pitcher had a 12-1 record. The game went into extra innings tied at 13-all. The Dodgers rallied with a seven-run 11th inning, but umpire Hank O'Day called the game by forfeit for the Dodgers because Phillies players stopped trying to get outs.

It was believed the Phillies were delaying the proceedings until nightfall in hopes that the game would be halted and the score would be reverted to the tie.

ESPN's Marly Rivera and The Associated Press contributed to this report.