All Orioles left-hander  Wei-Yin Chen could do was watch from the visiting dugout as the best start of his big league career – an effort so worthy of a win --  faded into a no-decision.

Reliever Pedro Strop, who allowed three singles, hit a batter, walked in a run and threw a wild pitch in the Mariners’ three-run eighth – couldn’t preserve Chen’s lead.

Chen had a perfect game going through 6 1/3 innings, just eight outs away from throwing the 23rd perfect game in baseball history and the first Orioles pitcher to do it.

But after the Orioles’ nailbiting 5-4 win -- Robert Andino’s solo homer with two outs in the ninth was the difference -- Chen shrugged off not getting a win despite tying a career-low for hits allowed and setting a new career high for strikeouts.

“That’s not a big deal,” Chen said through interpreter Tim Lin. “It’s a part of the game. We got the win today. The most important thing was that I helped the team get a W.”

Chen said he was as confident on the mound as he’s been this season. He was able to get ahead of hitters, keeping his pitch count down, and he had his best feel for his slider this season.

“This was probably the first time since I came to the states that I really felt good about my slider,” Chen said. “And once I established my first-pitch strike, I could easily execute my off-speed pitches.”

Until allowing a home run to Casper Wells with one out in the seventh inning, Chen retired 19 straight Mariners hitters. Of those 19, he issued an eye-popping 17 first-pitch strikes – with eight coming off fastballs and five off sliders.

“We had a really great effort out of Wei-Yin tonight and I wish we could have made it stand up,” Orioles manager Buck Showalter said. “It’s hard to be perfect for a long period of time. There’s failure and there’s success around the corner if you stay true to certain things.”

Chen was in control on the mound all night – a refreshing sign that the game is slowing down for the rookie as he reaches the unofficial midpoint of his first major league season at next week’s all-star break. He is slated to start Sunday in Anaheim in the final game of the first half.

“I think confidence was really important for me today,” Chen said. “I want to get better and better. Every step is a big step for me since I came here. Now I really don’t know what’s going to happen but I just do my job pitch by pitch, game by game  The one thing I want is to help the team win.”