CHICAGO -- On a night when the Mariners' offense was held in check, a two-out throwing error by shortstop Yuniesky Betancourt opened the door for the Cubs to score two runs in the fifth inning and capture a 3-2 Interleague victory in front of 40,163 at Wrigley Field on Wednesday.

Errors are as much a part of the game as hits and runs, but a miscue that prolongs an inning and leads to a loss is the most difficult to overlook. Betancourt knows the feeling all too well after what happened to him.

Betancourt's 15th error of the season allowed Mike Fontenot to come to bat in the fifth inning and deliver a two-run single to right field, snapping a 1-1 deadlock. It was Betancourt's seventh throwing error of the season, and with more than half the season remaining, he already has just five fewer errors than all of last season.

Several of Betancourt's throwing errors have been on routine throws, not difficult ones. He has a tendency to drop his arm on throws that he has to unload in a hurry, and the ball sinks as it nears the target.

Betancourt charged and fielded Ryan Theriot's two-hop chopper and made an on-the-run throw to first baseman Richie Sexson. The ball took one hop, and Sexson, who is good at receiving short-hopping throws in the dirt, was unable to make a clean scoop for the inning-ending out.

"I tried to pick it," Sexson said, "but in that situation, your first thought is, 'Knock it down.' If it gets past you, two runs score."

Two runs scored anyway as Fontenot slapped a single into right field off tough-luck loser Miguel Batista (7-5).

"Things happen when you play 162 games," manager Mike Hargrove said. "Yuniesky Betancourt is going to make a lot more plays that turn out in our favor than plays like he made tonight. It was just a bad throw."

The Mariners cut the two-run deficit in half in the sixth inning when Ichiro Suzuki tripled and scored on Jose Lopez's infield out. But an offense that has been so darn productive for more than a month finally met its match. Cubs starter Sean Marshall and right-handed closer Ryan Dempster retired 10 of the last 11 Mariners.

Perhaps it was the law of averages that finally caught up to the offense.

Coming into the middle game of the three-game series, the Mariners had been on a run-scoring binge unlike any during the past three seasons. During a 19-game stretch that started on May 24, the Ichiro-led offense batted .323 as a team, hiking the club batting average from .269 to .287, and averaged 7.2 runs per game.

Going back even further, the Mariners had 10 or more hits in 20 of the previous 26 games and combined to bat .316 (307-for-971), score 160 runs and pound out 81 extra-base hits.

But the team had little time to sit back and savor the accomplishment.

The hectic schedule the Mariners have been on the past six weeks -- two days off since May 1 -- and playing long games against the Indians and Cubs on back-to-back nights, prompted hitting coach Jeff Pentland to suggest that Wednesday night would be a good time to skip pregame batting practice.

Hargrove agreed, and the hitters that wanted to take some swings did so in the batting cage.

Seattle threatened to score the game's first run in the first inning, when Ichiro singled, advanced to second on a passed ball and went to third on a wild pitch. He bolted for home on a grounder hit to third base with one out but was thrown out, and the Mariners came away empty.

But the Mariners scored first anyway, when Sexson led off the second inning with his team-leading 10th home run, a shot to left-center.

The Cubs tied it in the third on a one-out walk, single to left field and ensuing error by Raul Ibanez, who slipped and fell just as he was throwing the ball to third base trying to get fleet-footed Felix Pie. Seattle played its infield back, willing to get an out for a run, and Cliff Floyd obliged with a grounder to second base.

Batista pitched a Batista-like game. He allowed numerous baserunners, but more often than not pitched out of trouble.

"After the first couple of innings, Marshall seemed to settle down," Hargrove said. "He pitched well, but not any better than our guy."