Los Angeles @ Boston preview

Last Meeting ( Aug 20, 2014 ) LA Angels 8, Boston 3

The Los Angeles Angels are enjoying the best record in the major leagues and a 1 1/2-game lead in the American League West but suddenly have a big hurdle to clear. The Angels could be without their best starting pitcher for a while starting when they attempt to finish off a four-game sweep of the host Boston Red Sox on Thursday. Garrett Richards went down with a patellar injury in his left knee on Wednesday that manager Mike Scioscia termed “significant.”

Los Angeles, which already subtracted Tyler Skaggs from the rotation due to Tommy John surgery, could have to find a way to replace their team leader in ERA, WHIP, WAR, strikeouts and batting-average against. Richards is expected to fly back to Los Angeles and undergo further testing on Thursday. The Red Sox are no strangers to waving away their best pitcher but are in a much different predicament while toiling at the bottom of the AL East and having lost four straight.

TV: 7:10 p.m. ET, FSN West (Los Angeles), NESN (Boston)

PITCHING MATCHUP: Angels RH Matt Shoemaker (11-4, 3.84 ERA) vs. Red Sox RH Rubby De La Rosa (4-4, 3.79)

Shoemaker is poised to step up in Richards’ absence and has allowed two or fewer earned runs in eight of his last 10 appearances. The Michigan native earned a win at Texas on Saturday by holding the Rangers to two runs on four hits while striking out six in 5 2/3 innings. Shoemaker came out of the bullpen against Boston to work the final three frames of a 19-inning affair on Aug. 9 and did not allow a base runner while striking out four to pick up the win.

De La Rosa suffered his first home loss of the season last time out, when he was knocked around for six runs on nine hits and four walks in four innings by the Houston Astros. The 25-year-old had allowed a total of two runs in 13 innings over his previous two turns. One of those came in Los Angeles, where De La Rosa held the Angels to one run while striking out eight in seven innings to earn a win on Aug. 10.

WALK-OFFS

1. Red Sox DH David Ortiz is 8-for-10 with two home runs and four walks in the series.

2. Los Angeles CF Mike Trout is 4-for-32 over his last eight games, dropping his batting average to .288.

3. Boston 3B Will Middlebrooks (right hamstring) sat out Wednesday and is day-to-day.

PREDICTION: Angels 5, Red Sox 3