CHICAGO -- Starlin Castro delivered a bases-loaded, walk-off single in the 11th inning to lift the Chicago Cubs to a 7-6 victory over the San Diego Padres on a chilly Saturday afternoon at Wrigley Field.

Castro's 11th-inning hit to shallow left field off Padres right-hander closer Craig Kimbrel scored Anthony Rizzo from third with the winning run.

Rizzo walked with one out, stole second and advanced to third while rookie third baseman Kris Bryant beat out an infield hit. Kimbrel then walked pinch-hitter David Ross to load the bases.

Kimbrel (0-1), who collected his fourth save in Friday's 5-4 win, entered in the 11th and took the loss.

Cubs left-hander Zac Rosscup (1-0) worked two innings for the victory.

The Cubs appeared on track for an easy win until the Padres rallied for four runs off two Chicago pitchers in the ninth to force a 6-6 tie.

Padres shortstop Justin Upton started the rally by driving in first baseman Yonder Alonso with a single and third baseman Will Middlebrooks' double scored right fielder Matt Kemp. Both runs came with none out against Cubs reliever Hector Rondon.

Second baseman Jedd Gyorko then hit into a fielder's choice to third that scored Upton.

Rondon struck out shortstop Alexi Amarista for the second out, but pinch-hitter Yangervis Solarte took a 2-2 pitch and singled to right to score Middlebrooks for the tie.

Cubs catcher Miguel Montero's sixth-inning solo home run to left broke a 2-2 deadlock. His two-run shot to right in the seventh drove in Castro and capped a three-run inning.

The multi-homer day was Montero's first since 2010 with the Washington Nationals and helped even the series at a game apiece.

Hendricks, who had no decision, worked six innings and allowed two runs and three hits, struck out eight and walked one.

Kemp gave San Diego a 2-0 lead in the first inning with his first home run of the season.

He took an 0-2 pitch off Hendricks and drove it into a 19 mph wind into Wrigley Field's unfinished left field bleachers, scoring Alonso.

Rizzo drove in the Cubs' first run with a fifth-inning bouncer down the right field line — officially labeled an error by Alonso. Still, it drove home second baseman Jonathan Herrera.

Bryant followed with his first major league hit and RBI with a looping single to center that scored center fielder Dexter Fowler to make it 2-2.

Padres manager Bud Black pulled starting right-hander Tyson Ross with a runner at first and two out in the sixth in favor of right-handed reliever Brandon Maurer. Castro followed with a base hit to left to drive in Rizzo for a 4-2 lead.

Ross pitched 5 2/3 innings and gave up three runs and five hits, walked five and struck out nine.

NOTES: After Friday's temperature flirted with 70 degrees, Saturday's conditions changed dramatically with game-time temperature of 43 degrees with a 34-degree wind chill. ... Through 11 games this season, the Padres had scored 48 runs (4.4 per game average), 20 more than the same period in 2014 and third highest in the National League. ... The Padres are 95-137 all time against the Cubs at Wrigley Field and 115-115 in San Diego. ... The Padres send RHP Andrew Cashner (0-2, 4.09 ERA) against Cubs LHP Jon Lester (0-1, 7.84 ERA) in Sunday's series finale. It's only Lester's second career meeting with the Padres. ... Cubs LHP Tsuyoshi Wada made his first start on a rehab assignment on Friday at Triple-A Iowa. He took a loss after working 4 2/3 innings while giving up one earned run and four hits. ... New 3B Kris Bryant is wearing uniform No. 17. First base coach Brandon Hyde gave it up and switched to No. 16. ... The teams meet again May 19-20 at Petco Park. The Cubs won last year's season series 5-2.