For more than two weeks, the Mariners’ starting pitching has been so good that Seattle suddenly finds itself in the surprising hunt for a postseason berth with its young, rebuilding club.

But that formula got waylaid on Tuesday by a second-inning line drive that knocked starter Ljay Newsome out of the game, and the Mariners’ bullpen gave up three home runs in a 6-5 loss that snapped Seattle’s six-game winning streak.

• Box score

The Mariners opened a 4-1 lead on a three-run double by J.P. Crawford in the top of the second, but Newsome -- making his second Major League start -- took a 100 mph shot from Brandon Crawford off his right wrist in the bottom of that frame.

“I thought he was throwing the ball pretty good,” Mariners manager Scott Servais said. “[The comebacker] changed the makeup of the game.”

Right-hander Brady Lail, acquired off waivers from the White Sox on Aug. 10, gave up two-run homers in the fourth and fifth, and the Giants took the lead on pinch-hitter Darin Ruf’s solo shot off rookie Anthony Misiewicz in the seventh.

Even with Newsome’s early departure, Seattle’s rotation has gone 10-3 with a 3.47 ERA over its past 17 games and the Mariners are 12-5 in that span, putting their record at 19-23.

But with seven relievers on the injured list and three others just traded to the Padres, the Mariners’ 10-man bullpen currently features seven rookies and came into the game with an American League-worst ERA of 6.30.

X-rays on Newsome’s hand were negative, and the Mariners' No. 30 prospect is listed as day to day, so that news was good for the 23-year-old right-hander.

“It actually feels pretty good right now, and I have full of motion in it,” Newsome said. “Hopefully I can make my next start. We’ll see how it feels.”

Newsome acknowledged that it was frustrating getting KO’d from just his second career start with a 4-1 lead.

“It’s kind of crazy,” he said. “I’ve been hit plenty of times. I’ve never come out of a game though. It was different. It was slow-mo almost. I saw it the whole way, I just couldn’t get my glove over, so it was just my initial reaction to get my arm up and protect myself.”

When Servais and Mariners athletic trainer Rob Nodine went to the mound, they could see seam marks from the ball on Newsome’s wrist, and he had no feeling in his hand.

“He got smoked pretty good,” Servais said. “We’ll have to wait and see if he’ll be available to make his next start. Hopefully he can.”

After trading Dan Altavilla and Taylor Williams on Aug. 31 and having several other key relievers sidelined by injuries, the Mariners have largely rebuilt their bullpen midstream. Two of their five relievers who pitched Tuesday -- Casey Sadler and Seth Frankoff -- were making their Mariner debuts, while Lail was making just his fourth appearance and first since Aug. 29.

“The guys out of the bullpen, a couple hadn’t pitched in quite a while, but they competed very, very well,” Servais said. “The Giants have a very good hitting team. They have one of the best hitting teams in the league and we saw it tonight. Their guys had good at-bats against us and got a couple balls up in the wind that got out of the ballpark.”

Servais left the park himself after being ejected for arguing balls and strikes in the eighth inning. It was his first ejection of the year and 12th of his managerial career.