Wong connected on a 3-2 fastball from rookie Raisel Iglesias (1-3) with two outs in the fourth, putting St. Louis ahead 4-1. Wong's second career grand slam easily cleared the right- field wall, landing in the home bullpen.
The Cardinals have won six of seven, are a big league-best 64-35 record and lead the NL Central by 6 ½ games.
Lynn (8-5) allowed one run and five hits in seven innings, improving to 7-3 against the Reds. He has won five of his last six decisions overall.
Trevor Rosenthal earned his 31st save in 33 chances after getting two days off.
