The win also marked the Cubs first series victory in 2014 and first since last September.
The Cardinals stranded two runners in the first then Castro made an over-the-shoulder catch in shallow left field to strand two more Cardinals.
The Cubs (11-17) also struggled early to put runners on. Castro doubled off the left field wall with one-out then advanced to third on Nate Schierholtz‘s groundout before he was stranded on third as Welington Castillo flied out to right in the fourth.
Lake doubled to left to leadoff the fifth, Olt and Luis Valbuena walked to load the bases before Rizzo grounded out to strand three for the Cubs.
Matt Adams singled with one-out in the sixth to end Arrieta’s outing. Arrieta gave up four hits, struck out seven and walked two over 5 1/3 innings. Brian Schlitter entered in relief and popped up the next two batter to end the sixth.
Lake’s two-run home run to center field off Cardinals’ starter Michael Wacha (2-2, 2.55 ERA) gave the Cubs a 2-0 lead in the sixth. It was his third of the season.
Rizzo’s solo home run to right off left-hander Randy Choate (0-0, 1.64 ERA) in the eighth. It was his third homer in as many days and his third off a lefty.
James Russell made one out in his first relief appearance since April 23.