KANSAS CITY, Mo. -- The defending World Series champion Kansas City Royals were all but written off in early May.

They were two games below .500, seven games out of first. Then came injuries to three All-Stars -- left fielder Alex Gordon (broken wrist), third baseman Mike Moustakas (torn ACL) and catcher Salvador Perez (bruised quad).

But the Royals are looking like champions again, winning five straight series.

Lorenzo Cain homered and Cheslor Cuthbert singled home the winning run as the Royals again came from behind to beat the Chicago White Sox 5-4 Sunday.

The White Sox have lost six straight and 14 of 18, while the Royals completed a series sweep and moved back into first place in the American League Central.

So the swagger is back.

"We never lost it," Cain said. "We hadn't been winning games, but at the same time, we've been right in the middle of everything. It's still early in the season. We've got a long way to go."

The White Sox's bullpen spoiled a solid outing by left-hander Chris Sale. Sale limited the Royals to two runs on seven hits, six of them singles, while striking out seven and walking two in seven innings. Sale, who failed to make it out of the fourth inning in losing Tuesday to the Indians, threw 80 strikes in 118 pitches.

"I don't know if it's chemistry as much as confidence," Royals manager Ned Yost said of the club's resiliency. "They just know what they are capable of doing. And they no matter what, they're not going to quit."

Nate Jones replaced Sale and gave up three runs on three hits, including Cain's homer and an Eric Hosmer double, and two walks, while retiring only one batter to take the loss. Jones walked Brett Eibner with the bases loaded in the eighth to tie the score.

Matt Albers relieved Jones and yielded Cuthbert's infield single that scored pinch runner Jarrod Dyson with the go-ahead run.

"I feel like against us, you've got to play nine innings," Cain said. "You've got to finish it off. You just never what's going to happen, especially playing us. We just continue our attitude, never quit, never die, we find ways to stay in the ballgame, get back in the ballgames and hopefully win them."

The White Sox know first-hand the Royals can and will come back.

Adam Eaton, who had three White Sox hits, had a groundout in the fifth, scoring Avisal Garcia to tie the game. Austin Jackson's two-out single brought home Tyler Saladino to put the White Sox up 3-2.

Jackson added another RBI in the seventh with a sacrifice fly off Kansas City reliever Luke Jackson. Paulo Orlando made a spectacular catch of Jackson's fly with the bases loaded. That gave the White Sox a 4-2 lead, but one they could not hold.

Royals starter Edinson Volquez surrendered three runs on seven hits and a walk over six innings.

The Royals jumped on Sale for two runs in the first inning and it could have been more. With one out, Whit Merrifield singled and has hit safely in his first eight career starts. Cain's double to center scored Merrifield. Hosmer laced a single to left, bringing Cain home. Next Kendrys Morales scorched a Sale offering to deep center, but Austin Jackson tracked it down. Hosmer, believing the ball was over Jackson's head, was off with contact and around second base when the ball was caught. He could not get back to first time, completing an 8-6-3 inning-ending double play.

"Rough first inning, but you know the guys you have behind you, allows you to kind of just forget about it," Sale said. "Just try to get as deep into the game as you can. We know this is a team that's going to put the ball in play, they're going to be hard on you. From that point forward it was just about eating innings and getting us as deep into the ballgame as I could, trying to keep it where it was so we could try to get on top."

The White Sox got a run back in the bottom of the inning off Volquez on consecutive singles by Jose Abreu, Brett Lawrie and Dioner Navarro. With Lawrie on third and Navarro on second, Volquez struck out Garcia and retired Saladino on a fly ball to shallow center to prevent further damage.

"It's a long season," Jones said. "It's got ups and downs. We're just on one of those downs. We've just got to grind through it. We'll turn it around. We've got another game tomorrow, so we'll concentrate on New York. We're going through a downer these last few games, but we'll turn it around."

Jackson left in the eighth inning with toe turf.

"I never had it before, so I really didn't know what I was feeling," Jackson said. "We tried to tape it up, but it was better in that situation to take some precautionary, just to get out of the game. You don't want to risk injuring it any further than that."

NOTES: An MRI detected Royals three-time All-Star C Salvador Perez has a bruised left quadriceps after a collision Saturday with 3B Cheslor Cuthbert. Manager Ned Yost said Perez is expected to be out 7-10 days and was not placed on the 15-day disabled list. "You don't want to have to put him on the DL and he's ready to play in eight days and has to sit there for another week," Yost said. ... The Royals called up C Tony Cruz, who hit .204 in 69 games last season with St. Louis, from Triple-A Omaha. ... The Royals sent RHP Peter Moylan, who had allowed two runs on 10 hits and two walks in 7 1/3 innings, to the Storm Chasers. With Moylan's demotion, the Royals will go with 12 pitchers. ... SS Jimmy Rollins, who is 1-for-14 off Royals starter RHP Edinson Volquez, was not in the White Sox lineup for the second straight game. ... The White Sox continue this 11-day trip Monday with a series against the Mets. White Sox LHP Jose Quintana and Mets RHP Matt Harvey are the probables Monday in New York. ... The Royals continue their homestand with three games against the Rays. Royals RHP Ian Kennedy and Rays RHP Matt Andriese are the Memorial Day starters.