Nursing a 10-point lead and having driven from their own 10-yard line to the Chicago Bears' 6-yard line on the opening drive of the second half Sunday night, the San Francisco 49ers suddenly went conservative.

Three straight runs netted the Niners nothing after Frank Gore gained one yard, Carlos Hyde lost two and Gore again picked up one.

Forced to kick a 24-yard field goal, the 49ers left four points on the field after holding onto the ball for more than nine minutes and taking a 20-7 lead. They would not score again, though, and they would fall to the Bears, 28-20.

"When you're up like that," Gore said after the game, "you've got to go for the kill. We let them get back into the game. We didn't finish and they beat us."

Heading into Sunday's showdown at the Arizona Cardinals, you have to wonder if the 49ers will be more aggressive if they face a similar situation.

"Could we have called a different play?" coach Jim Harbaugh mused Monday.

"'Oh, you ran a running play.' It didn't work. 'Could you have used a different play and that could have worked?' Yeah, we'd love to go back and try the different play now. But, that's in all these situations when you look back -- one worked, one didn't. Sure you'd like to try the other, but you're not in that position."

The Cardinals, who are 2-0 with victories over the San Diego Chargers at home and at the New York Giants, will just have to wait and see how aggressive or conservative the Niners will be on Sunday.