Kershaw's streak was halted at 37 innings when Polanco hit the first pitch of the bottom half of the first into the centerfield seats.
Polanco has now led off two straight games for Pittsburgh with a solo home run. The 23-year-old has six on the season.
Polanco's homer was the first run given up by Kershaw since July 3. Over his last four starts heading into Friday, Kershaw pitched 34 scoreless innings with 45 strikeouts and one walk.
Kershaw, who has won back-to-back NL Cy Young Awards, is 9–6 overall on the season with a 2.37 ERA and 0.912 WHIP.
The Dodgers and Pirates opened up a three-game series on Friday.
- Molly Geary