BOSTON -- Jon Lester gave Boston's battered rotation another boost.
He also showed that Jonathan Papelbon isn't the only outstanding rookie pitcher on the Red Sox.
Lester said he was surprised by his success in his first eight major league starts but "I knew I could perform at this level."
The emergence of Lester, who started the season at Triple-A Pawtucket, has come at an important time for Boston. David Wells and Matt Clement are on the disabled list and Tim Wakefield left Monday night's 5-4 win over Kansas City after four innings with an upper back strain.
"He's jumped right in and been a huge member of our staff," Red Sox manager Terry Francona said. "He's young, but that was a good example of what he can do."
Lester gave up just a clean single to center field in the second to Mark Teahen, the only Royal to reach second base. The left-hander, who made his major league debut June 10, struck out four, walked four, allowed only five balls to leave the infield and dropped his ERA to 2.38.
"I hadn't ever seen him before and I was pretty impressed," Royals manager Buddy Bell said. "They have some pretty good-looking young pitchers, that's for sure."
Papelbon, who came up in the Red Sox system with Lester, retired the Royals in the ninth on a strikeout and two grounders for his major league-leading 28th save in 31 opportunities.
"These are the moments you cherish in baseball," Papelbon said, "especially with us coming up through the ranks together."
Boston scored in the fifth on a double by Jason Varitek and an RBI single by Alex Gonzalez.
Brandon Duckworth (1-3) allowed only that run and five hits in six innings, but the Royals still suffered their seventh loss in eight games.
"We played well enough to win, but you've got to give credit to Lester," Duckworth said. "Whenever he got a guy on, it seemed like he was able to get a groundball and get a double play."
One run was enough against baseball's worst team.
Francona said he didn't know if Lester would have gotten the same results against a better team.
"You play who you play. That's what matters," he said.
Lester pitched very efficiently, throwing 100 pitches, including 57 strikes. In his previous seven starts, he averaged 103 pitches and 5 1/3 innings.
"Any time you can go deep into the game, it gives you a big confidence booster," Lester said.
The shutout was Boston's second in four games after going without one for the first 88 games of the season.
After Teahen grounded a single through the middle with one out, he stole second but was stranded.
Lester walked Esteban German with one out in the first then struck out the next two batters. Mark Grudzielanek led off the fourth with a walk and was caught stealing. Tony Graffanino walked with two outs in that inning but was forced out at second. Graffanino walked again in the seventh but was out on an inning-ending double play.
"He's got some good stuff," Kansas City's Joey Gathright said of Lester, "but we should have done a lot better than that."
After Gonzalez singled home Varitek in the fifth, the Red Sox threatened in the sixth when Manny Ramirez doubled with two outs into the left-field corner on a high fly that the strong wind took away from David DeJesus, who overran the ball. Trot Nixon was walked intentionally before Mike Lowell flew out.
- Varitek broke Carlton Fisk's team record when he caught his 991st game for the Red Sox.
- Kansas City's streak of 36 straight games with at least one double, matching a club record, ended.
- The Royals have lost 10 of their last 11 games at Fenway Park and are 8-19 against lefty starters.
- Boston is 30-13 at Fenway, its best record through 43 games there since 1979.
- Boston's last combined one-hitter was by David Wells, Mike Timlin and Keith Foulke in a 7-0 win over Cincinnati on June 14 last year.