Mathis allowed one hit and struck out three over seven innings as Triple-A Pawtucket blanked Norfolk, 4-0, on Monday.
The big league veteran set down the first 14 batters of the game before Ronny Paulino tripled to right field with two outs in the fifth inning. He got Chris Robinson to ground out to shortstop Jose Iglesias to end the threat and retired the side in order in the sixth and seventh.
"I was just throwing a lot of strikes and being aggressive," Mathis said. "They were hitting the ball on the ground and right at the defense. It was one of those nights were I was throwing well, but when they hit the ball it was right at someone."
Mathis, who has appeared in 45 games over three Major League seasons, is 3-2 with a 4.23 ERA in nine starts for the Red Sox. In his previous start on May 16 against Durham, the 28-year-old right-hander surrendered four runs on 10 hits over 5 1/3 innings. Mathis credited better preparation and execution for Monday's results.
"I just had a better plan," he said. "I had a better idea of what I was trying to do and being aggressive and not getting worked up if I fell behind a guy. I was concentrating on keeping the ball down. In the starts where I've struggled I've left the ball up in the zone. Tonight I was aggressive, but making sure I was down in the zone."
Kevin Youkilis, making possibly his final rehab start for Pawtucket, doubled home a run and walked twice, raising his average to .364. Mathis said playing alongside the third baseman has been a great experience.
"He's very professional, he gets his work done, and even though this is Triple-A, he takes everything serious and has good at-bats," Mathis said. "He's a good guy, he talks to everyone, he's fun to have around. It's one of those things where it's nice to have him around. He's been great."
On the opposite side of the field stood 15-year big leaguer Miguel Tejada, the 2002 American League MVP who signed a Minor League contract with the Orioles on May 8. Mathis held Tejada without a hit in three trips to the plate.
Iglesias, the Red Sox's No. 11 prospect, drove in a run and Pedro Ciriaco was 2-for-5 with an RBI.
Will Inman struck out two and allowed a hit in an inning of relief while Garrett Mock tossed a perfect ninth for Pawtucket.