Cincinnati's Joey Votto fractured his left thumb during a 10-inning, 1-0 win over the Chicago White Sox on Wednesday.
Votto was hit by a Dallas Keuchel pitch in the fourth inning. Votto remained in the game, but in the sixth was replaced at first base by Kyle Farmer.
Votto is not expected to need surgery but could miss up to a month. Hit by a pitch for the 61st time, Votto is hitting .286 on the homestand, which included his 300th home run. He has raised his average to .226 with five homers and 17 RBIs.
Kyle Farmer is among the options at first.
Jesse Winker hit a winning single in the 10th inning after Chicago's Leury Garcia was caught stealing in the top half.
Cincinnati's Sonny Gray and Keuchel both pitched shutout ball, allowing two hits each in seven innings.
It was only the fourth scoreless tie through nine innings in Great American Ball Park's history, the first since 2010.
Cincinnati stopped its 18-inning scoreless streak as Liam Hendriks (1-1) lost for the first time since signing a $54 million, four-year contract with the White Sox as a free agent.
With automatic runner Tucker Barnhart on second, Nick Senzel singled against Hendriks leading off the 10th as Barnhart took third. Jesse Winker fouled off three pitches before lining the eighth offering from Hendricks into center field. Barnhart scored without a throw.
Hendriks got Barnhart to ground into a bases-loaded groundout that ended the ninth, then started the 10th as the automatic runner on second.
Lucas Sims (1-1) walked Yasmani Grandal leading off. Garcia grounded into a forceout that left runners at the corners and, with Billy Hamilton at the plate, Barnhart threw out Garcia trying to steal second.
Hamilton then struck out.
Chicago, trying to contend despite losing outfielders Eloy Jimenez and Luis Robert to injuries this season, lost for the fourth time in its last 12 games.
Gray struck out eight. He has 19 strikeouts over his last 12 2/3 innings.
Gray extended his major league record of allowing six or fewer hits to 48 consecutive starts.
Both teams were a combined 0 for 9 with runners in scoring position through eight innings, stranding 11 runners. There were 29 runners left on base in all, 15 by the Reds.
Carlos Rodon (4-0, 0.72 ERA) starts Friday at Kansas City. He is the first White Sox pitcher to win his first four starts opening a season since Chris Sale won nine to begin 2016. Hear the action on WHOW with pregame at 6:30 and first pitch at 7:10.
