The pitch count was on David Price’s mind when he walked to the mound in the seventh inning, but another number was stuck in his head.

He didn’t want to leave the mound without getting 21 outs. He already had 18, but even though he was rolling, his pitch count was creeping dangerously close to the century mark.

There wasn’t much room to allow a base runner, Price figured, not if he wanted to finish the inning.

“If somebody gets on, I could’ve been done,’’ he said. “I didn’t want to get taken out of the game during an inning. I wanted to be able to finish that seventh inning.’’

He made sure that wasn’t a problem.

Price sat Chris Colabello down with a changeup that had Colabello taking a Wiffle ball swing. He used the same pitch to render Russell Martin helpless.

The only batter left to keep Price from tying a bow on the Blue Jays lineup was Darwin Barney, and he found himself in an 0-and-2 hole in a hurry.

Going back to the changeup made the most sense. Price had the Blue Jays off-balance with it all day. But on the last of his 107 pitches, Price reached back for the gas.

He tucked a 93-mile-per-hour fastball low at Barney’s knees. All Barney could do was watch it go by.

While Barney turned to plate umpire Angel Hernandez to figure out what just went by him, Price strode slowly back to the Red Sox dugout.

His seven innings of work more or less muzzled the Blue Jays in a 4-2 win Saturday at Fenway Park that gave the Sox three straight victories.

“To me, that’s the least amount of innings I can go,’’ Price said. “I want to get 21 outs every five days — I want to get 27 outs, but 21 is what I want to be the minimum every five days I step out there — and knowing that one pitch could kind of ruin my day, I definitely tried to lock in a little bit more.’’

The performance also washed away even the slightest worries after a big inning spoiled Price’s Fenway debut last Monday. He was eager to get back on the mound after giving up five runs to the Orioles.

“I hadn’t thrown the ball the way I know that I can my first two starts,’’ Price said. “And to throw the baseball the way that I did today against the Blue Jays, which is an extremely, extremely good hitting team, it feels good.’’

His nine strikeouts made him the just the second Red Sox pitcher in the past century (and the only lefthander) to strike out at least eight batters in his first three games with the team. He’s the only starter on the Sox staff to finish the seventh inning this season.

“It’s almost like he gave you the feeling that there was closer mentality in that final inning of work,’’ said manager John Farrell. “He finished his game today with a strong exclamation point to a solid outing for him. But any time you go through that lineup three times, you’ve got very consistent location and multiple looks to get through a really strong lineup.’’

The only trouble Price ran into came early in the afternoon.

After he struck out Kevin Pillar on three pitches to start the game, Josh Donaldson shot a liner to center field for a triple. The next batter, Jose Bautista, launched a fly ball off the Monster to plate Donaldson, but Bautista got greedy rounding second and ended up being thrown out at third.

But outside of Donaldson (2 for 4, run) and Bautista (2 for 4, run, RBI), Price kept the Blue Jays off-balance with fastballs, curveballs, cutters, and changeups, throwing 74 strikes. His strongest weapon was the changeup, which he threw for 27 strikes and nine swings and misses.

“He’s got such a wipeout, put-away changeup that he can throw it multiple times consecutively,’’ Farrell said. “I don’t know that there’s really any one area or any one pitch that opposing hitters can sit on and look for.’’

“He’s that talented and has that type of repertoire and just quality stuff across the board.’’

The Sox gave Price a cushion with a four-run third. Xander Bogaerts sent a line drive screaming into the Monster seats for a three-run homer and Travis Shaw added an RBI single.

Six days after Marco Estrada baffled the Sox lineup with his own changeup, the Sox adjusted by tagging the Jays starter for eight of their nine hits.

“With his pitch mix, you have to respect that changeup and you can’t look to rush out there and look to have your point of contact out in the front edge of the plate,’’ Farrell said. “He’ll use that aggressiveness to his advantage. I think our guys did a very good job of letting the ball travel a little bit deeper in the strike zone and using the whole field as a result.’’

The Jays climbed within striking distance when Edwin Encarnacion laced an RBI double to center in the fourth to make it 4-2, but that’s all the noise Toronto would make.

It was the first time Price faced his former team since signing a seven-year, $217 million deal with the Sox in December.

No active pitcher has a higher winning percentage against the Jays than Price, who improved to 17-2 against them.

“We staked him to a lead after the four-run third inning and he went out and continued to keep the game under control and just an outstanding job getting us through seven innings,’’ Farrell said. “Really good to see him work his full assortment of pitches. He was really strong today.’’

Julian Benbow can be reached at jbenbow@globe.com.