KANSAS CITY, Mo.

Will Middlebrooks was sitting in front of his locker, paying no attention to the horde of reporters heading his way, when Red Sox ace Jon Lester gave him fair warning.

“Here they come,” Lester said. “Not like you didn’t have a good game or anything.”

The rookie third baseman homered down each of the lines Monday night, pacing a Boston attack which included homers by David Ortiz and Dustin Pedroia and resulted in an 11-5 victory over the Kansas City Royals that snapped a maddening fivegame losing streak.

Middlebrooks, called up last week when Kevin Youkilis went on the disabled list, hit a three-run shot in the first inning and a two-run homer in the eighth, becoming the first player in Red Sox history with at least one extra-base hit in each of his first four major league games.

He also hit a grand slam in Boston’s 17-inning loss to Baltimore the previous night.

“I just tried to carry over the way I started out this year,” said Middlebrooks, who was hitting .333 at Triple- A Pawtucket when he got called up. “Just wanted to help the team win.”

Felix Doubront (2-1) allowed all five Kansas City runs over 6.1 innings, giving the Red Sox bullpen a muchneeded rest. Boston used up every available arm against the Orioles, forcing left-fielder Darnell McDonald to finish the 9-6 defeat.

Doubront left protecting a two-run cushion with the bases loaded in the seventh inning, but Vincente Padilla got Billy Butler to chop into an inning-ending double-play to preserve the lead, and the Red Sox added four more runs in the eighth to put it away.

Padilla wrapped up the game for the 34-year-old’s sixth career save.

The Royals’ Jonathan Sanchez (1-2) was pounded for six runs in three-plus innings, the 11th straight time the former Giants starter failed to last more than five innings.

Kansas City pitchers are averaging fewer than five per start, worst in the major leagues.

Doubront wasn’t great, but he gave manager Bobby Valentine enough.

The left-hander got into trouble every inning but the fourth, yet he somehow managed to limit the damage each time. Doubront allowed seven hits and three walks on 111 pitches.

The Red Sox wound up with 16 hits, two shy of their season high, and the four homers was second only to the five they hit against Tampa Bay on April 14.

Notes — Boston pitcher Daisuke Matsuzaka (Tommy John surgery) pitched 4.2 innings for Pawtucket on Monday in the third of his five scheduled rehab starts … Royals RHP Greg Holland (ribcage) left for what will likely be two rehab appearances at Double-A Northwest Arkansas.