Matt Olson belted a walk-off home run off Josh Hader in the 10th inning Tuesday, July 30, to give the host Oakland Athletics a 3-2 win over the Milwaukee Brewers in the opener of a three-game interleague series in Northern California.

Chris Bassitt and five relievers combined on a seven-hitter, helping the A's prevail in the first meeting between the clubs since 2016.

Olson's homer, his 22nd of the season, was the left-handed hitter's ninth off a lefty pitcher this season, and just the second of his career in extra innings. It was the fourth home run Hader (1-4) surrendered to a left-handed batter this season.

Blake Treinen (5-3), who pitched a 1-2-3 top of the 10th with two strikeouts, got the win.

The crowd-pleasing finish capped a roller-coaster ride over the final three innings, during which the A's twice blew one-run leads.

After the A's had scored the game's only run of the first seven innings on a two-out double by Olson in the third inning, the Brewers got even in the eighth on a two-out, RBI single by Yasmani Grandal.

Oakland went back on top when Khris Davis snapped a 29-game homerless drought with a tiebreaking solo shot with two outs in the bottom of the eighth. But again the Brewers caught up, this time on a solo homer by Eric Thames with one out in the ninth off Liam Hendriks.

The homers were No. 17 of the season for Davis, No. 15 for Thames.

Both starters had outstanding outings.

Bassitt worked six shutout innings, allowing three hits. He walked one, struck out six and left with a 1-0 lead.

Brewers righty Adrian Houser nearly matched Bassitt pitch for pitch. He was charged with one run on three hits in five innings, with one walk and six strikeouts.

Davis (three) and Olson (two) combined for five of the seven hits for the A's, who improved to 6-3 in interleague play.

Orlando Arcia had three hits for the Brewers, who fell to 3-8 in interleague contests.