SAN DIEGO -- Things went from bad to worse for the Angels in their series opener against the Padres on Monday night.

Superstar Mike Trout left the game in the eighth inning with a left wrist injury after fouling a ball back while facing right-hander Nick Martinez. It came after the Angels struggled with runners in scoring position and the bullpen imploded. Trout departed with the Angels down by six runs in an eventual 10-3 loss at Petco Park.

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Trout, a three-time AL MVP and 11-time All-Star, underwent further testing after the game, including an X-ray exam, and appeared concerned about his wrist. 

“Just took a swing and something felt uncomfortable,” Trout said. “Just waiting on getting some scans and hoping for the best. I’m praying for the results to come back clean. But it doesn’t feel great. Hopefully, it’s just a sprained wrist.”

Trout, who stayed healthy all season before Monday, added that he’s never had a wrist injury, so he didn’t know what to expect.

“I can’t really describe the pain I felt,” Trout said. “I’ve never felt that pain ever. I’ve never had wrist problems or anything. Just a freak thing.”

Trout, who was 2-for-3 with a walk before sustaining the injury, was replaced by Mickey Moniak. Moniak struck out on the next pitch, but because Trout started the at-bat and left with an 0-2 count, he was charged with the K and finished 2-for-4.

Trout, who was selected as an All-Star for the 11th time and as a starter for the 10th straight year on Thursday, has been heating up at the plate, so it would be a huge blow if he misses any extended time.

Trout, 31, has a slash line of .333/.438/.648 over his past 15 games, with four homers, three doubles and seven RBIs. And now he’s in danger of missing another All-Star Game after missing the previous two due to injuries.

“That’s another thing,” Trout said. “I’ve started to see the ball better. It’s just tough.”

Trout has slashed .263/.369/.493 with 18 homers, 14 doubles and 44 RBIs in 81 games this season. His OPS of .862 is a step down from his otherworldly career OPS of .994, but he worked to fix his mechanics in mid-June and had been looking more like his old self.

The Angels could have to lean on their improved depth yet again, as they’ve also dealt with injuries to key players such as catcher Logan O’Hoppe, shortstop Zach Neto and infielder Brandon Drury. Veteran third baseman Anthony Rendon has landed on the injured list twice.

Jo Adell would be the top candidate to get called up if Trout lands on the injured list, and the outfielder has been having an incredible season at Triple-A Salt Lake. Adell hit his Minor League-leading 23rd homer of the year on Monday and homered in his lone game with the Angels this year.

“We've talked all along about our depth,” Angels manager Phil Nevin said. “It's been tested, and we’ve even added to it. We’ve lost some big pieces. We’ve talked about how it’s the next guy up. Same thing in this case -- give somebody the opportunity to get more looks and get more bats depending on what the outcome of Mike's tests are. So we’ll see how it goes.”

Trout’s injury came on a frustrating night for the Angels. They racked up 14 hits and six walks but simply couldn’t bring them in, as their season-long struggles with runners in scoring position came to the surface again.

Situational hitting has been a source of frustration for the Angels this year, as their .332 team on-base percentage ranks fifth in the Majors and should lead to more runs being scored. But they’re hitting just .246 with runners in scoring position, which ranks tied for 24th among the 30 MLB clubs.

The Angels couldn’t score against lefty Blake Snell through five innings despite seven hits and four walks and finally broke through in the sixth with two runs. But the bullpen struggled, as relievers Victor Mederos, Tucker Davidson and Sam Bachman each gave up two runs to make it a rout for the Padres.

They were also hurt by not turning a double play in the first before right-hander Jaime Barria surrendered a three-run homer to Xander Bogaerts. 

Nevin lamented both their lack of success with runners in scoring position and the defensive miscue in the first that cost Barria three runs and roughly 15 pitches.

“We had a lot left on and just didn't get the big hit when we needed it,” Nevin said. “The game should have been a lot different.”