"Johnson to have MRI exam today

The rollicking start to the Giants' homestand came to a sobering halt Sunday when left-hander Randy Johnson abruptly exited his start in the fourth inning because of a left-shoulder strain during a 7-1 loss to the Houston Astros.

The extent of the injury won't be clear until Johnson has an MRI exam today.

Johnson was in no mood to discuss his status after the game, saying, "It's a strain, I'm getting an MRI. That's all I have to say." Then he brusquely walked off, presumably for additional treatment.

The first sign of trouble came when Johnson swung awkwardly during a strikeout in a third-inning at-bat, wincing as the bat sailed out of his hands and to the backstop. Manager Bruce Bochy said Johnson told him he had experienced a similar follow through before, and that he felt fine to pitch the fourth inning. Johnson's velocity dipped noticeably (he allowed two home runs in the fourth), but Bochy said Johnson said he didn't become concerned until he made a wild sidearm throw to first base. One pitch after the run-scoring throwing error, Johnson summoned trainer Dave Groeschner and, after a brief conversation, headed off the field.

"It was very scary,'' catcher Bengie Molina said. "He usually throws 89, 90, 91 (mph), and all of the sudden you see this guy throwing 82. We just hope and pray nothing happened to him seriously and he's OK for his next start.'' "