The Oakland Athletics go for a three-game sweep and their ninth straight win in an effort to widen their gap over the visiting Houston Astros when the American League West powers continue their low-scoring series on Sunday afternoon.

A pair of impressive rookies -- Oakland left-hander Jesus Luzardo (0-0, 2.31 ERA) and Houston righty Cristian Javier (1-0, 1.42) -- are the scheduled starters.

After a 13-inning marathon Friday that featured 12 pitchers and 12 2/3 innings of relief work, the A's Frankie Montas and Astros' Framber Valdez gave their respective bullpens a break in a starters' duel Saturday, a game won 3-1 by Oakland.

Marcus Semien, the hero of Friday's 3-2 win with a walk-off single, led off Saturday's game with a home run, his first of the season, giving the A's a lead they never relinquished.

The walk-off/leadoff homer two-day double was a first in A's history, and came after Semien had opened the season just 11-for-62 (.177).

The All-Star shortstop also singled, stole a base and scored Oakland's second run Saturday, completing a two-hit day A's manager Bob Melvin attributed to momentum created by the walk-off about 14 hours earlier.

"How can it not?" he asked reporters after Saturday's win. "You see this. ... You play that long. Those games are very difficult to lose and great to win. For him to get a big hit in that situation, I don't know how it can't be good for him."

The two wins extended Oakland's winning streak to eight games and pushed them 4 1/2 in front of Houston, which has won the last three AL West titles. There are just 45 games remaining in the truncated season.

Luzardo will attempt to build upon the margin when he makes his second start of the season. He pitched well, but got no decision Tuesday against Texas, throwing five two-hit, shutout innings in a 5-1 win.

The 22-year-old Peruvian made his big-league debut against the Astros in Houston last September, allowing a home run to Martin Maldonado but no other hits in three innings of relief in a 5-3 victory.

He's 0-0 with a 3.00 ERA in his career against the Astros.

Javier will be making his third start, having limited the Los Angeles Dodgers and Arizona Diamondbacks to a total of six hits and three runs over 11 2/3 innings in his first two.

The 23-year-old from the Dominican Republic has never faced the A's.

Javier has been starting in place of staff ace Justin Verlander, who suffered a strained right forearm on Opening Night.

Astros manager Dusty Baker was not encouraging when asked for a progress report before Saturday's loss.

"Verlander, to my knowledge, is not progressing as quickly as he'd like to," the veteran skipper told reporters. "But does he ever? Verlander wanted to pitch yesterday."

Pitching has dominated the first two games of the showdown series, with hitters combining for 31 hits and three homers in 22 innings, while the pitchers have recorded 41 strikeouts.