The most challenging part of the Astros’ abbreviated 2020 schedule is yet to come, with first-place showdowns at Oakland against the A’s and in Los Angeles against the Dodgers looming. It’s make-or-break week for the Astros if they’re to win a fourth consecutive American League West title.

Things can’t go much worse for the Astros than they did this weekend in Anaheim, where the Angels pulled off four last at-bat wins, capped by Sunday’s 9-5 loss in the series finale at Angel Stadium. The Astros will head to Oakland for a five-game series beginning Monday trailing the first-place A’s by 3 1/2 games.

• Box score

“We’re still in a good position,” Astros manager Dusty Baker said. “Going into Oakland, we’ve certainly got to turn it around.”

Astros starter Framber Valdez needed to work deep Sunday to rescue Houston’s overworked bullpen, and he battled for seven-plus innings, throwing 108 pitches on a 106-degree afternoon, but gave up career highs in hits (11) and runs (eight). Houston pitchers allowed 31 runs in 31 2/3 innings in the series.

“It was tough,” Valdez said. “It was a battle on two fronts today -- had to battle the heat and the opposition. It was tough for me, but I did my best to stay focused throughout the game and attack the strike zone. I felt I did that. Unfortunately, it didn’t come out the way we wanted in the end.”

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The series started ominously, with Friday night starter Lance McCullers Jr. unable to record an out and, two days later, landing on the injured list with neck nerve irritation. That Angels beat up on Houston's beleaguered bullpen from there, coming from behind to win both games of Saturday’s doubleheader.

“We’re still trying to recover from that first day, the early exit by McCullers, and it was downhill from there,” Baker said. “Oh boy, that was tough to take. They were really swinging the bats.”

Sunday’s game began with more promise. The Astros led, 3-0, after a two-run homer by Kyle Tucker in the first inning and a leadoff homer in the second by Aledmys Díaz. The Angels pushed three runs across in the third to take a 4-3 lead, and the Astros scored two in the seventh -- including a 461-foot homer by Carlos Correa -- to tie the game.

“This upcoming series against the A’s is a big series,” said Tucker, who’s slashing .414/.485/.948 with six homers and 26 RBIs in the last 17 games. “We can go in there and win some games and try and get back closer to first place and close the gap, at least a little bit.”

Valdez, pushing 100 pitches, went back to the mound to start the eighth and gave up an infield hit and two more singles, with Jared Walsh’s RBI hit putting the Angels ahead and ending Valdez’s day. The Angels scored four in the eighth, with three runs charged to Valdez and one to Chris Devenski.

The Astros will play five games in four days in Oakland and only two next weekend at Dodger Stadium. The A’s and Dodgers represent the only teams with winning records remaining on the last third of Houston’s schedule.

“We’ve got to rise to the occasion, and we usually do,” Baker said. “I anticipate much of the same. I’m not saying we were playing down to the competition, because these guys are hot. They're really hot. Knock on wood, I don’t think the clubs we’re facing this week are going to be any hotter than these guys. We have to believe in ourselves and think lucky.”