The pitch by Zack Greinke that struck Carlos Quentin on the biceps appeared innocent enough.

The Dodgers were ahead of the San Diego Padres by only a run. There were no outs in the sixth inning. The count was full.

But Quentin charged the mound and sparked a Thursday night melee that could be as costly for the Dodgers as it was temper-igniting.

Greinke, appeared to be injured in a shoulder-to-shoulder hit from Quentin, was escorted off the field at Petco Park by trainer Sue Falsone. He was later diagnosed with a fractured left collarbone.

Matt Kemp and Jerry Hairston Jr. were ejected.

As for the game, the Dodgers won, 3-2, on an eighth-inning solo home run by Juan Uribe.

Quentin, the Padres' left fielder, was hit on the wrist in the series opener by Ronald Belisario and missed the game on Wednesday night.

Quentin also had a personal history with Greinke, as Greinke had hit him twice before.

Then again, a lot of pitchers have hit Quentin. The pitch he took on the left arm from Greinke was the 97th pitch to strike him since the start of the 2008 season, making him the most-hit player in the major leagues in the last five-plus seasons.

No matter.

When Greinke hit Quentin with the Dodgers holding on to a 2-1 edge, Quentin dropped his bat and glared toward the mound. Greinke appeared to say something to him.

Quentin, who is listed by the Padres at 6 feet 2 and 240 pounds, attacked. Greinke, considerably lighter at 195 pounds, dropped his glove.