Angels pitcher Garrett Richards leaves game on stretcher

Angels pitcher Garrett Richards had to be taken off the field on a stretcher after injuring his...

Angels pitcher Garrett Richards had to be taken off the field on a stretcher after injuring his knee during the second inning against the Red Sox in Boston on Wednesday, Aug. 20, 2014. (Mark L. Baer/USA TODAY Sports)

The Sports Xchange

, Last Updated: 9:28 PM ET

Los Angeles Angels right-hander Garrett Richards left the Fenway Park field on a stretcher Wednesday after he twisted his legs while covering first base.

With one out in the second inning and runners on first and second, Boston Red Sox third baseman Brock Holt grounded to first base. Albert Pujols threw to second base for a force, and as Richards approached the first base bag, his legs buckled. He went down in pain.

There was no play at first base, and the Angels threw to third to try to catch Xander Bogaerts overrunning the bag. Bogaerts dived back safely into third, and Holt was safe at first.

Cory Rasmus replaced Richards on the mound, and he struck out second baseman Dustin Pedroia to end the inning.

Tied for third in the American League with 13 wins, Richards is one of the mainstays of the Angels' pitching staff. He began the night with a 2.53 ERA that ranked fifth in the AL, though his ERA rose to 2.61 after he was allowed two runs in 1 2/3 innings against the Red Sox.

From the start of June through mid-July, Richards was one of the hottest pitchers in the major leagues. He went 7-0 with a 1.25 ERA over a nine-start stretch, striking out 70 and walking 17 over 64 2/3 innings.

The streak ended with consecutive losses, but Richards bounced back to throw a five-hit shutout against the Los Angeles Dodgers on Aug. 4. He then fired seven sharp innings in a no-decision against Boston on Aug. 9, and he earned a road win against the Texas Rangers on Aug. 15.