KANSAS CITY, Mo. — Will Middlebrooks homered down each of the lines, David Ortiz and Dustin Pedroia also went deep, and the Boston Red Sox pounded the Kansas City Royals 11-5 on Monday night to snap a five-game 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.

Felix Doubront (2-1) allowed all five Kansas City runs over 61/3 innings, giving the Red Sox bullpen a much-needed rest. Boston used up every available arm against the Orioles, forcing left fielder Darnell McDonald to finish the 9-6 defeat.

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

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 his sixth career save.

Red Sox Manager Bobby Valentine refused to make any roster moves to bolster the bullpen after their marathon at Fenway Park, reasoning that nobody deserved to get sent to the minors.

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

Doubront 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.

Of course, it’s easier to pitch with a lead.

Adrian Gonzalez gave him that with an RBI single in the first, but Middlebrooks piled on moments later when he belted a three-run shot that just skirted the right-field foul pole.

Kansas City got half of the runs back on an RBI groundout by Brayan Pena and a sacrifice fly by Chris Getz, but the Royals repeatedly failed to put together a big inning.

Ortiz homered to right field in the third inning. Kelly Shoppach led off the fourth with his first career triple, chasing Sanchez from the game, and Pedroia greeted reliever Nate Adcock by pounding a two-run homer into the seats in right-center field.

The Royals still trailed 7-4 when Doubront came out for the seventh inning.

He allowed a leadoff single by Pena and one-out hits by Alcides Escobar and Jarrod Dyson before getting Alex Gordon into an 0-2 hole. Gordon managed to work back for a full-count walk, bringing in a run and chasing Doubront from the game.

That’s when Padilla took care of Butler with a chopping double-play grounder to second base.

Boston then piled on in the eighth inning.

NOTES: Daisuke Matsuzaka tossed 42/3 scoreless innings for Triple-A Pawtucket in the third of his scheduled five rehab starts.

Matsuzaka’s start was pushed back three days because of a neck injury. He threw 49 of his 87 pitches for strikes.