SEATTLE -- Red Sox catcher Jarrod Saltalamacchia couldn't have been prouder of the performance turned in Thursday night by Boston starter Franklin Morales.

Of his own performance, the veteran catcher was much less enthused.

Morales, starting for the Sox for the third time after 22 relief appearances, dominated the Seattle Mariners for seven innings.

He threw his fastball on the corners at 96 mph, produced a splitter the Mariners could do nothing with but hit it into the ground and mixed in a curve that just keeps getting better.

Through it all, he didn't allow a run, giving up just three hits and two walks.

"That was a great performance by Morales," Saltalamacchia said. "He controlled both sides of the plate with his fastball and kept them off balance. This is a guy who not too long ago was throwing one inning. Tonight he threw seven, and he was great."

The trouble for Morales, and Saltalamacchia, was that Seattle's Felix Hernandez was throwing equally well. Hernandez shut out a Boston offense that had scored five or more runs in nine of the previous 10 games, giving up five singles, three of them on broken bats.

So the game was scoreless into the bottom of the ninth. And it would have been scoreless into the 10th, too, had Saltalamacchia been able to hold on to a throw from right fielder Cody Ross.

Casper Wells, who had doubled off Boston reliever Scott Atchison, tried to score on pinch hitter John Jaso's single. Ross came up throwing and put the ball on the spot. Umpire Adrian Johnson was ready to call Wells out, but when the ball went off the end of Saltalamacchia's glove and squirted free, the Red Sox were facing a rare 1-0 loss.

"It's a play we practice a lot," Ross said. "But it's tough. Sometimes it just doesn't work out. It was going to be tough tonight. King Felix was as good as I've ever seen him."

Saltalamacchia wasn't about to let himself off the hook quite as easily.

Cody Ross' throw was there in time to get Casper Wells, but Jarrod Saltalamacchia couldn't hold on. AP Photo/Elaine Thompson

"I've got to do a better job holding on there," Saltalamacchia said. "It was a good throw. I knew Cody would get me the ball with a chance. It was good and low. I reached for the ball and I tried to block the plate. And the ball went off the end of the glove.

"If I caught it, he was out."

The only upside for Saltalamacchia was that he caught a series of pitches from Morales that indicate the left-hander could force his way into the rotation to stay.

"He was throwing his fastball 96 [mph] on both sides of the plate," Saltalamacchia said. "That's not that easy to do. Not many can. And he was throwing a nice splitter and mixing his curve in. He was nasty."

Manager Bobby Valentine is quickly becoming a Morales fan, too. He plucked the lefty out of the bullpen when injuries started to chip away at the Boston rotation.

And now that Josh Beckett is due to come back Saturday from a stint on the disabled list, Valentine would rather go to a six-man rotation than boot Morales out of the mix.

"I'm very impressed," Valentine said. "I like the way he maintained his velocity, and he had a very good changeup tonight. In the last [seventh] inning, he had to pitch his way out of it.

"He threw changeups to [Miguel] Olivo and didn't get frustrated with the infield hit. He did a heck of a job."

Morales knows he doesn't have the history in the rotation that some of his competitors do. On the other hand, he was a starter in the Colorado organization through the 2008 season, and he's never quite let go of the belief that he could take the ball every five days and be competitive.

"Bobby's given me the chance, and I like it," Morales said. "I'm very confident in myself right now. I don't think I have to prove myself. I just have to keep pitching and not think about it too much.

"I feel pretty good about this game. But at the same time, King Felix was pitching pretty good too. It was going to be tough to score off him."

For his part, Hernandez said the Red Sox could do a lot worse than keep giving the ball to Morales.

"He's got a good arm and real good stuff," said Hernandez, who remembers Morales from the lefty's days with the Rockies. "He did a great job for them tonight."