CHICAGO -- Lou Piniella is a frustrated manager in a tough spot: He is lacking options.
"What am I supposed to do?" Piniella said. "I can start changing lineups around and let my bench play. I can do that."
Losers of seven of nine, the Cubs are playing without injured third baseman Aramis Ramirez (calf), and Piniella had use to Carlos Zambrano as a pinch hitter in the eighth and play catcher Koyie Hill at third in the 10th.
The Cubs' only substitutes right now are outfielders Micah Hoffpauir, whom Piniella doesn't want to start in right because of defense, and the weak-hitting Joey Gathright. Slumping catcher Geovany Soto didn't start.
"It's a big concern," Piniella said. "Big concern."
Defense is a concern for the Cubs as well.
Alfredo Amezaga doubled and scored on Ryan Theriot's fielding error for the go-ahead run in the 10th and Cantu homered and drove in four runs for the Marlins. Florida tied it in the eighth when Marmol threw away Maybin's sacrifice attempt.
"When you play those games so tightly late in the game, it's usually a base on balls or an error that's going to crack the game open," Marlins manager Fredi Gonzalez said. "There's no secret about that. We were glad that we were able to take advantage of it."
Theriot committed two of the Cubs' three errors.
Amezaga led off the 10th with a drive Aaron Heilman (2-1) that popped out of a diving Reed Johnson's glove for a double. Wes Helms walked before Amezaga scored when Theriot couldn't come up with Derrek Lee's throw to second for the force on Emilio Bonifacio's grounder.
"When everything is going right, you're going to take advantage," Amezaga said. "I feel pretty happy that I helped the team."
Heilman failed to record an out in the inning, giving up six runs -- five earned -- on three hits, while walking two.
"We're not playing the way we know we can play," Lee said. "We need to change it, we need to fix it. April's over now, it's time to turn it around."
Renyel Pinto (2-0) got one out for the win.
Amezaga helped the cause in the ninth with a diving stop of Johnson's grounder to short that would've scored Theriot from third.
Bradley got his first hit as a Cub at Wrigley Field: a home run in the fifth.
Fontenot connected on the next pitch from Chris Volstad for consecutive homers to give Chicago a 2-0 lead.
Bradley came into the game hitting .097 (3-for-31) in 13 games this season, missing time with a groin strain.
Trailing 2-1 in the eighth, pinch-hitter Ross Gload was walked by Marmol, who then walked Bonifacio. Gload scored when Marmol threw away Maybin's bunt toward third, tying it 2-all.
Cantu homered off Sean Marshall to start the seventh to make it 2-1.
Volstad retired the first 10 hitters, before Theriot singled in the fourth. ... Zambrano had a pinch-hit single with two outs in the eighth. ... Cubs 3B Aramis Ramirez ran in the outfield before Thursday's game in front of manager Lou Piniella. Ramirez had an MRI earlier in the day on his strained left calf that didn't show a tear. ... The Cubs flew minor league infielder Bobby Scales to Chicago from Triple-A Iowa in case Ramirez needed to go on the DL, but then sent the career minor leaguer home. ... Marlins SS Hanley Ramirez missed his third straight game with a bruised right wrist. Manager Fredi Gonzalez said he expected Ramirez to return sometime during the Marlins' four-game series in Chicago. ... Most of the Wrigley Field press box was following the Bulls triple-overtime victory over Boston, which played on one TV.