Guthrie looks to extend a career-high 15-inning scoreless streak Sunday and help the Royals complete their first three-game sweep of the White Sox in nine years.Kansas City acquired Guthrie (2-3, 4.02 ERA) in a trade with Colorado on July 19 and he posted a 7.71 ERA over his first three starts. He's been a much different pitcher lately, however, giving up no runs in his last two outings.After scattering five hits in eight innings of a 2-1 win at Chicago on Aug. 8, the right-hander surrendered three hits in seven innings of a 5-0 victory over Oakland on Tuesday.Guthrie has struck out 14 while walking two in those starts."It's not really fluky stuff," manager Ned Yost said. "You can see where this could be extended out start after start. I'm really liking what I'm seeing right now."Guthrie isn't the only Kansas City starter that's been successful against the White Sox (65-54). Saturday's 9-4 loss was Chicago's fourth straight to Kansas City, which has won 12 of the last 18 meetings.Bruce Chen didn't give up a run until the sixth, Alcides Escobar went 4 for 5 and Billy Butler had three hits and drove in three runs.Mike Moustakas hit a three-run homer in the eighth to put the game out of reach after Adam Dunn's 400th career homer in the top of the inning pulled Chicago to within 5-4."We've very confident coming in here each day," Butler said. "We believe in each other. We honestly believe coming in each day that we're going to win."The Royals (53-66) have won 12 of 18 overall and have an opportunity to sweep the White Sox for the first time since 2003. A victory in the finale would also give them five straight wins in the series in a single season for the first time since 1991.Chicago, which remained 1 1/2 games ahead of second-place Detroit in the Central, continues to struggle offensively against Kansas City. It's 16 for 87 (.184) with runners in scoring position against the Royals this year, going 3 for 14 in this series.The White Sox didn't help themselves with a season-high four errors Saturday."It's just about the worst-case scenario, getting it like this," Dunn said of his milestone home run. "We've played two bad games. Tonight was a disaster from the get-go. Obviously, I would have wanted it to come in a win."They'll try to provide some more support for Jose Quintana (5-2, 2.77), who picked up his first win since July 5 by limiting Toronto to two runs in 6 2/3 innings of a 3-2 victory on Tuesday.The rookie had posted a 4.46 ERA over six starts between June 29 and July 20, but has settled down over his last two. Despite reaching the 100-pitch mark for the eighth time in nine starts, Quintana thinks he'll be fine for the stretch run."I feel good, I've definitely never pitched this many innings but it's one of those things," he told the White Sox's official website. "My arm feels good and I'm putting in the work and I feel like I can definitely go the distance."Quintana is winless in two starts against the Royals this year. He was effective opposite Guthrie earlier this month, allowing two solo homers and three other hits over seven innings of a tough-luck 2-1 loss.