Updated

Oakland, CA (SportsNetwork.com) - Jon Lester tossed 6 2/3 solid innings in his first start since being traded from Boston, and his new Oakland teammates backed him up with eight runs in the fifth inning as the A's took down the Kansas City Royals, 8-3.

Lester (11-7), who has not lost since June 7, struck out three and allowed three runs on nine hits while only allowing one walk.

"I felt fine physically," Lester said. "Some times those extra days can help you or hurt you and it did a little bit of both for me today. I was a little sloppy with my cutter ... I would've liked to finish that seventh, but I got a little bit ahead of myself and I couldn't."

Jason Vargas (8-5) had a perfect game going through four innings, but was lit up in the fifth. He allowed seven hits and four runs during the frame before being removed.

"I left some balls up, we didn't play defense and that's what happens," Vargas said. "We unraveled. As a whole, we weren't very good in the fifth inning."

Vargas lasted 4 1/3 innings and was charged with seven runs in his first start since July 8.

Alberto Callaspo, Josh Reddick, Nick Punto, Jed Lowrie and Jonny Gomes each had RBI singles during the explosive inning for the Athletics, who tied the three-game series at one apiece. Josh Donaldson pushed a run across by drawing a walk.

Nori Aoki finished with two hits, one RBI and one run scored in the Royals' first loss in four games.

The Royals scored first with a run in the third. Alcides Escobar led off with a single and Aoki walked to put two men on. After Omar Infante moved the runners over with a bunt, Salvador Perez hit a sacrifice fly to center to score Escobar.

The Athletics then picked up eight runs in a disastrous fifth inning for the Royals. Derek Norris doubled, Gomes singled and Stephen Vogt reached on a fielder's choice to load the bases. Callaspo and Reddick's singles scored Gomes and Vogt, then Punto hit one into right to score Callaspo.

After Sam Fuld singled on a bunt to re-load the bases, Lowrie scored Reddick with a grounder into left. Punto grabbed his leg, however, and fell to the ground as he rounded third.

Eric Sogard came on to pinch-run for Punto and Aaron Crow replaced Vargas on the mound with one out and the bases still loaded. Crow walked the first batter he saw, Donaldson, and Gomes hit a line drive for his second single of the inning, scoring Fuld and Lowrie. The ball kept rolling past Alex Gordon in left field, allowing Donaldson to also score and Gomes to make it to third.

Scott Downs replaced Crow to get Vogt to ground out for the last out of the inning.

Aoki and Christian Colon hit back-to-back RBI singles in the seventh to cut the lead to 8-3.

Jesse Chavez gave up a single and a walk in the ninth, but managed to get Colon to ground out to end the game.

Game Notes

The Athletics batted 13 times and recorded a season-high eight hits during their eight-run fifth inning ... Ryan Cook took over for Lester in the seventh inning and pitched a perfect eighth, extending his scoreless streak to 15 2/3 innings ... Prior to the game, the Royals placed Eric Hosmer on the 15- day disabled list and activated Vargas from the 15-day DL to make the start. Vargas had been sidelined after having an appendectomy.