Athletics manager Bob Melvin indicated Saturday that shortstop Hiroyuki Nakajima is finally running pain-free, the Oakland Tribune reports.

"He's going down the line 100 percent and moving good on defense," Melvin told the Tribune. "Next up for him is to get multiple-hit games back-to-back."

Nakajima's rehab assignment can only last until May 23, at which point he'll either have to be placed on the active roster or assigned to the minor leagues. He's recovering from a left hamstring injury.

Athletics catcher John Jaso returned from a leg injury Saturday, going 0 for 3 with two strikeouts as the team's designated hitter in a 2-1 win over the Royals. He ended up missing just one game with the injury.

The hitless game dropped Jaso's line to .250/.339/.313 with just one home run in 128 plate appearances this season.

Angels relief pitcher Sean Burnett started his rehab assignment with Class A Inland Empire Saturday night, surrendering a solo home run while pitching one inning. The homer was the only hit off Burnett in the appearance.

Working his way back from forearm tightness, Burnett is expected to be activated from the disabled list before Tuesday's game.

Athletics closer Grant Balfour stayed perfect in save opportunites by recording his eighth save Saturday against the Royals, walking one batter in a scoreless inning. His ERA dropped to 1.56 in 17 1/3 innings this season.

Royals starting pitcher Ervin Santana allowed just two earned runs on four hits and three walks in seven innings Saturday against the A's, but it wasn't enough to avoid his third loss of the season as the Royals fell, 2-1. He struck out five on the day.

Santana has managed to last at least six innings in each of his eight starts this year while compiling a 2.77 ERA. He'll face his former team, the Angels, Thursday.

Padres catcher Yasmani Grandal, who is serving a 50-game suspension, began his minor-league rehab assignment with Triple-A Tucson Saturday.

Grandal went 2 for 4 with a run scored and an RBI. He is not scheduled to play Sunday, but will resume his rehab on Monday. He is eligible to return from suspension on May 28.

Athletics starting pitcher Tommy Milone notched his fourth win of the season by holding the Royals to one earned run in six innings, allowing five hits and three walks while striking out four.

The win broke up a string of losses in five straight game for Milone, moving him to 4-5 on the year. He takes that record, a 3.47 ERA and a 49:12 K:BB ratio into a matchup with the Astros Friday.

Padres closer Huston Street, who was pegged with a loss his last time out, picked up the save Saturday night against the Nationals.

Street worked his way around two walks as he pitched a scoreless ninth inning to secure a 2-1 victory. He struck out one and improved his ERA to 4.42 after notching his 10th save of the season.

Nationals pitcher Jordan Zimmermann stayed sharp as he struck out six but suffered his second loss of the season Saturday night against the Padres.

Zimmermann (7-2), who made his ninth start of the season, allowed a solo home run to Yonder Alonso in the second. He gave up a run-scoring single to Everth Cabrera that broke a tied game in the eighth. The right-hander was charged with two runs -- one earned -- and seven hits over eight innings of work in a 2-1 defeat.

Zimmermann has allowed one earned run or less in four of his last five starts. He is scheduled to make his next start Friday at home against the Phillies. He went 1-2 with a 3.71 ERA in three starts against Philadelphia last season.

Twins catcher Joe Mauer returned from back stiffness to go 2 for 5 with one double and one run as the Twins' designated hitter in a 12-6 loss to the Red Sox Saturday.

The two-hit performance extends Mauer's hitting streak to 15 games and raises his season line to .351/.430/.503 in 172 plate appearances.