(SportsNetwork.com) - Jered Weaver tries to bounce back from a shaky Opening Day start on Saturday when the Los Angeles Angels of Anaheim continue their three-game series with the Kansas City Royals at Angel Stadium.

Weaver absorbed the loss on Monday in Seattle, as he allowed four runs and eight hits - five extra-base hits - in six innings.

A little alarming for the Angels was the fact that his fastball averaged 83.5 mph, the lowest of his career. That's been the trend in recent seasons for Weaver, who still won 18 games a year ago.

"I gotta do a better job myself," Weaver said. "A lot of pitches up, falling behind in counts. I had to pretty much battle the whole game. It's a tough way to get it going, but we have two more against them."

Weaver has faced the Royals 12 times and is 7-4 against them with a 2.21 ERA.

Kansas City, meanwhile, will turn to righty Jeremy Guthrie, who made 32 starts for the Royals last season. Guthrie was 13-11 a year ago with a 4.13 ERA.

In 13 games (12 starts) against the Angels Guthrie is 3-5 with a 4.43 ERA.

Kansas City improved to 4-0 on Friday, as Jason Vargas pitched six effective innings and Lorenzo Cain drove in two runs in the Royals' 4-2 win.

Kendrys Morales homered against his former team to help the reigning AL champions win four straight to start a season for the first time since 2003 when they opened the season with nine consecutive wins.

Vargas (1-0) allowed five hits and a pair of runs while fanning three. Jason Frasor and Kelvin Herrera each pitched a scoreless frame to bridge the gap to Wade Davis. The closer struck out three batters in the ninth to pick up his first save.

"Jason threw great. He executed his pitches and kept them off-balance. Defense is a big part of our game and it was tonight," Royals manager Ned Yost said.

Hector Santiago (0-1) gave up six hits and three runs over 5 1/3 innings for the Angels, who won their final two contests of a season-opening series at Seattle.

"Hector struggled with his first 50 pitches, then he found his rhythm," Angels manager Mike Scioscia said. "He used a lot of pitches early, but he'll be better next time."