CHICAGO - Anthony Rizzo capped his return to the Cubs lineup with a walk-off home run in the ninth inning that gave Chicago a 1-0 win over the Cincinnati Reds on Monday night.

Rizzo had missed the last 18 games due to a back problem but drove a pitch from Pedro Villarreal (0-1) over the wall in centre field. Rizzo's homer was his 31st of the season and gave Hector Rondon (4-4) the win after he tossed a scoreless inning of relief.

Travis Wood didn't get any run support and couldn't earn his ninth win of the season despite producing one of his best outings of the year. Wood threw six scoreless innings, allowed only three hits, and lowered his ERA to 4.86.

Cincinnati starter Alfredo Simon gave up five hits in seven innings.

Until the ninth, the Cubs didn't do much at the plate even though they Rizzo and Jorge Soler in the lineup together for the first time.

Soler went 1 for 3 after he missed a weekend series in Pittsburgh due to the birth of a child.

Simon had been one of Cincinnati's most pleasant first-half surprises but he had been struggling. He entered with a 2-7 record and 4.96 ERA in the second half.

Simon, who is 3-0 against the Cubs this season, was looking for his second consecutive win but didn't get the support needed for the victory. He might have if Cubs centre fielder Arismendy Alcantara didn't run down Kristopher Negron's drive to right-centre with two outs in the eighth and speedy Billy Hamilton on first.

The Cubs loaded the bases against Simon in the first inning on two singles and a walk, but didn't score. Welington Castillo popped out to end the inning.

Cincinnati got its first chance in the third, starting the inning with a single and a walk, but Negron flew out to right.

TRAINER'S ROOM

Reds: 1B Joey Votto took infield during pregame warmups but didn't take part in batting practice. Votto (left quadriceps) hasn't played for the Reds since July 5 but did take underhand flips in a batting cage Sunday.

Cubs: Manager Rick Renteria said SS Starlin Castro (sprained left ankle) is improving but "he's more not likely to be able to come back" this season. Renteria also said SP Edwin Jackson (right lat strain) would throw a simulated game this week.

UP NEXT

Reds: RHP Johnny Cueto and Cubs RHP Jake Arrieta will face off on Tuesday. Cueto (18-8) will attempt to match Dodgers LHP Clayton Kershaw for the most wins in baseball this season. Cueto is 5-1 with a 1.84 ERA in his last nine starts against the Cubs. Arrieta (8-5) leads the Cubs with a 2.82 ERA.