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5/23/2014 8:28 P.M. ET

Villanueva put bullpen back in order, Renteria says

SAN DIEGO -- Cubs manager Rick Renteria credited right-handed reliever Carlos Villanueva for getting his bullpen back in order.

Villanueva relieved starter Jake Arrieta to open the seventh inning Thursday night and worked the final three innings. No other reliever even got up in the Cubs bullpen on a night when Renteria wanted to stay away from at least four of his relievers.

"Carlos did a great job spelling the bullpen yesterday," Renteria said on Friday. "Thanks to him, we're back in great shape. Everyone is available tonight, except for Villaneuva."

Villaneuva allowed three hits with three strikeouts in three scoreless innings.

Rizzo shows dramatic improvement vs. lefties

SAN DIEGO -- Anthony Rizzo's struggles against left-handed pitchers have been well documented.

Coming into this season, Rizzo had a career batting average of .194 against left-handed pitchers with 12 homers and 43 RBIs in 320 at-bats. Last season, Rizzo hit .189 against left-handers with seven homers and 23 RBIs in 190 at-bats.

But the first baseman's two-run, go-ahead home run off Padres left-handed starter Eric Stults Thursday night was his fourth of the season in just 50 at-bats. Rizzo is hitting .300 against left-handed pitchers this season with 10 walks for a .419 on-base percentage. His .560 slugging percentage against left-handers this season gives him an OPS of .979 -- more than 300 points high than his career OPS of .668 against left-handers. His career on-base percentage against left-handed pitchers coming into the season was .272.

"It's a constant battle," Rizzo said Thursday night of his gains against left-handed pitchers. On another front, Rizzo has 21 walks and only 14 strikeouts and a .446 on-base percentage and a .967 OPS in his last 20 games dating back to April 30.

Ruggiano closer to being activated

SAN DIEGO -- Manager Rick Renteria said the Cubs are getting closer to making an activation decision on outfielder Justin Ruggiano, who has been on the disabled list since April 24 with a left hamstring strain.

Ruggiano played back-to-back games for Triple-A Iowa Thursday and Friday for the first time since he suffered the injury.

"We'll see how he feels tomorrow and re-evaluate the situation," said Renteria. "Back-to-back games is one of the tests."

Renteria said right-handed pitcher Pedro Strop, who has been on the disabled list since May 7 with a right groin strain, could be nearing a rehab assignment.

Worth noting

• Left fielder Junior Lake was 2-for-4 Thursday night and is hitting .370 (17-for-46) with four doubles, two homers and 10 RBIs in his last 13 games since May 8.

Bill Center is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.