OAKLAND, Calif. — The last time the Yankees flew out to the West Coast to begin a road trip, they immediately had a 10-run outburst against the Mariners.

Of course, those were simpler times, when they were still able to write Aaron Judge into their lineup instead of thinking about his toe.

On Tuesday, despite coming off a winning homestand and opening a series against the worst team in baseball, the Yankees fell flat in a 2-1 loss to the Athletics at Oakland Coliseum.

Jhony Brito pitched well in his second start back in the majors, but did not receive enough run support from his offense.

The Yankees (43-36) recorded seven hits off right-hander Paul Blackburn and the Athletics’ bullpen but stranded four runners over the final two innings.

One of those hits was a home run from Josh Donaldson in his first start since being benched for three straight games over the weekend, but it came with nobody on base in the fifth inning.

In the eighth inning, the Yankees had a chance to strike when Trevor May walked DJ LeMahieu and Anthony Rizzo on four pitches each and then fell behind 3-0 to Giancarlo Stanton with two outs.

But Stanton took a called strike and fouled off two pitches before hitting a chopper to third base to end the threat.

Stanton was unable to carry over any momentum from Sunday, when he chipped in an RBI single to the Yankees’ series-clinching win over the Rangers.

Instead, he fell to 7-for-62 since returning from the IL on June 2.

Then in the ninth, Gleyber Torres led off with a pinch-hit single before Donaldson struck out looking and Billy McKinney flew out.

Anthony Volpe extended the inning with an infield single but Kyle Higashioka struck out to end it, allowing the Athletics (21-60) to win for just the second time in their last 12 games.

It was the second straight quality outing from Brito since he was called up from Triple-A last week to help fill the rotation spot left open by Nestor Cortes’ shoulder injury.

After throwing 5 ²/₃ scoreless innings against the Mariners, Brito followed up with 5 ²/₃ innings of two-run ball against the Athletics.

Ex-Yankee Tyler Wade collected the first hit off Brito with a triple to the right-field corner in the third inning.

He came around to score on a single by Esteury Ruiz to put the Athletics up 1-0.

The Yankees threatened to tie it back up in the top of the fourth when Anthony Rizzo roped a one-out double to right field.

But Blackburn, who entered the night with a 4.21 ERA, followed by striking out Stanton and Jake Bauers to strand Rizzo at second.

Then in the bottom of the inning, Seth Brown crushed a solo home run off a sinker that caught too much of the plate and made it 2-0.

The Yankees got one run back in the fifth inning on Donaldson’s solo blast, a 423-foot shot off a slider down the middle.

It marked Donaldson’s seventh home run of the season, accounting for almost all of his nine hits through his 22nd game.

In a bright spot for the Yankees, Volpe continued to look better at the plate, going 3-for-4 with three singles.

But after his second single in the seventh inning, his perfect stolen base streak to begin his big-league career came to an end at 15-for-15.

He was thrown out trying to steal second with two outs — a call that the Yankees challenged, but after replay review, it was upheld.