The Kansas City Royals were on a mission to overtake the Detroit Tigers in the American League Central and not even baseball's best team could slow their charge. Kansas City moved into first place in the division Monday and will go for its ninth consecutive victory against the visiting Oakland Athletics on Tuesday. "You want to be in first place. Our goal was to get back to first place," Royals manager Ned Yost said. "Now our goal is to stay in first place."Kansas City has a daunting challenge to maintain its slight edge over the Tigers when it faces nemesis Jon Lester for the third time since July 20. Acquired from Boston at the trade deadline, Lester registered a pair of victories over the Royals in a 13-day span to improve to 8-3 with a 1.65 ERA against them - the lowest ERA by any pitcher versus Kansas City. With Oakland holding a 3 1/2-game lead in the AL West, Lester takes a 6-0 mark and 1.21 ERA in his last 10 starts overall into Tuesday's matchup. TV: 8:10 p.m. ET, CSN California (Oakland), FSN Kansas CityPITCHING MATCHUP: Athletics LH Jon Lester (12-7, 2.44 ERA) vs. Royals RH Jeremy Guthrie (8-9, 4.35)Lester beat the Royals in his Oakland debut, allowing three runs in 6 2/3 innings, and followed that up with his first complete game of the year, limiting Minnesota to three hits and striking out eight. It was the 10th consecutive start in which Lester has permitted three or fewer runs. Lester, who is 1-3 in four starts at Kauffman Stadium despite a 2.74 ERA, has stymied Royals DH Billy Butler (4-for-25) and OF Alex Gordon (3-for-22).Guthrie is also coming off his first complete game of the season, holding Arizona to two runs on seven hits to win his third straight start. Guthrie beat the Athletics in Oakland in his previous turn with six scoreless innings of three-hit ball to improve to 4-4 with a 4.29 ERA in 11 appearances (10 starts) against them. He is doing a better job of keeping the ball in the park, giving up only three of his 19 homers in the past six games.WALK-OFFS1. The Royals acquired OF Josh Willingham in a trade with Minnesota on Monday.2. Athletics LF Brandon Moss drove in a pair of runs Monday, ending a nine-game drought and giving him 74 RBIs this season.3. Royals RHP Wade Davis has not allowed a run in 18 consecutive appearances.PREDICTION: Athletics 3, Royals 2