When Lance Lynn shed weight and started rethinking his workouts he explained one of the motivating reasons was the late-summer wilt he couldn’t seem to avoid. The innings would mount, the temperature would climb, and his strength would evaporate. He tried different approaches the past two years and still was fatigued in the fifth month. August proved his undoing. This summer it has been his unveiling. The Cardinals’ ascendant starter eclipsed one of the league’s leading aces, Cincinnati righthander Johnny Cueto, and threw the Cardinals to a series sweep of their rivals. Lynn pitched seven shutout innings Wednesday before a thunderstorm parked over Busch Stadium and kept him from an eighth. The Cardinals piled on and then held on for a 7-3 victory, and Lynn savored every inning he did what Cueto could not. “It didn’t hurt my feelings one bit beating him,” Lynn said. “You see all the leaderboards and you see his name at the top and I outpitched him. As a competitor when you get into situations like that you want to rise up and you want to outduel whoever you’re facing, especially when it’s someone like that.” A 58-minute rain delay after the seventh inning did what the Reds failed to do — knock Lynn (14-8) from the game — but also led to Cincinnati’s last-gasp rally and a crack at Cardinals closer Trevor Rosenthal. The Cardinals committed two errors in the ninth that led to three runs and rushed Rosenthal into the game when manager Mike Matheny had hoped to give him the night off. Rosenthal faced the tying run at the plate in a game the Cardinals once led by seven runs. He retired All-Star Todd Frazier on a groundout to secure his 37th save and complete Lynn’s gem. The Cardinals head east this afternoon to Philadelphia after a 6-1 home stand that was laced with more offense and more consistent offense than any previous stretch this season. For only the second time the Cardinals have scored at least four runs in eight consecutive games, and they drummed the Reds with 37 hits in three days. Jon Jay had three of the 10 hits Wednesday and Jhonny Peralta had three of the seven RBIs. The Cardinals chased Cueto (15-7) from the game in the sixth inning and raised his ERA from 2.06 to 2.24. The Reds meander home after a 1-6 road trip that skidded to a halt with five losses in four days. When Cincinnati started the voyage, it trailed first-place Milwaukee by 5½ games. The Reds return to Ohio trailing the second-place Cardinals by 8½.