"This was a great series for us," Lester said.
McDonald scored one run and drove in another to help the Red Sox win their sixth consecutive game in Toronto. The Red Sox swept successive series of three games or more in this city for the first time since 1981 and 1982.
"It was huge for us," catcher Jason Varitek said. "Obviously we didn't swing the bats great but we scored just enough, and it started with Jon's pitching."
McDonald had one of the best views of that.
"Wow. It's a beautiful thing to watch from center field," McDonald said. "It looked like he got better as the game went on."
Boston has won seven of nine since being swept in a four-game series by Tampa Bay, and Lester sees more good things ahead now that the Red Sox (11-11) have returned to .500.
"Once we get on a bit of a roll, it's hard to stop us," Lester said. "If we keep putting games together like that, pitching and hitting when we need to, things will take care of themselves."
Toronto, which has lost five straight and nine of 12, was shut out for the second time in four games. The Blue Jays have not scored in 17 innings.
"We shouldn't have lost three games," Toronto's Aaron Hill said. "Yeah, they pitched good, but still, we're better than that."
Jonathan Papelbon worked the ninth for his seventh save.
Lester (1-2) came in winless in four starts with a 6.23 ERA but was brilliant in this one.
He allowed only one hit, a leadoff double by Vernon Wells in the second, and followed by retiring 14 consecutive batters, a streak that ended with Mike McCoy's two-out walk in the sixth. Lester finished that inning by striking out Hill looking, and ended his outing with a 1-2-3 seventh.
"He pitched really well," manager Terry Francona said. "He ought to feel good about himself. He looks great."
Hill, who went 0-4 with three strikeouts, was also full of praise for Lester.
"That's the best I've seen him," Hill said. "He's always had good stuff and a good arm, but he had everything in any count."
With Lester silencing the Blue Jays offense, Toronto's fans didn't have much to cheer about. One of the loudest ovations of the night from the 15,276 fans came when word spread that the Montreal Canadiens scored a third-period goal against the Washington Capitals in Game 7 of their first-round playoff series.
The Red Sox doubled their lead against reliever Casey Janssen in the seventh when McDonald grounded a two-out single through the left side.
"He's done a good job," Francona said of McDonald. "He's sitting down there in the nine hole but he's got big hits. He's played a pretty good center field. I think he's excited about his opportunity and he's looking to make the most of it."
Making his second start of the season, Blue Jays left-hander Brett Cecil (1-1) allowed one run and five hits in six innings. He walked one and struck out three.
"[Lester] was a few pitches better than I was," Cecil said.
- Red Sox OF Mike Cameron, out since April 18 with an abdominal strain, is expected to resume running this weekend, Francona said.
- Blue Jays LHP Rommie Lewis made his major league debut with a scoreless ninth.