CHICAGO – Sam Bradford should not have been on the field Monday night. Not like that, not in that condition.

He didn't look healthy enough or sharp enough to be an effective quarterback, which was obvious from his first pass, which sailed over the head of Stefon Diggs. Typically, Bradford makes that throw in his sleep.

Bradford returned as the Vikings starting quarterback in a 20-17 victory against the Chicago Bears after missing three games because of a flare-up in his surgically repaired left knee. He was listed as questionable on the injury report.

Vikings coach Mike Zimmer defended the decision to play Bradford, who finally was lifted late in the first half after aggravating his injury, according to Zimmer.

"We wouldn't put him on the field if he wasn't healthy enough to play," Zimmer said. "He was very confident about it. He felt good about it. The medical people felt good about it. I don't think there was any doubt whatsoever he was ready to play."

Fine, but once Bradford reinjured himself on a sack, he should have been removed immediately. Instead, Zimmer stuck with him even when it became painfully apparent that Bradford could not protect himself.

Tom Wallace — Star Tribune, Star Tribune
Minnesota Vikings quarterback Sam Bradford (8) was sacked in the end zone by Chicago Bears outside linebacker Leonard Floyd (94) for a safety in the first quarter.

Twice he fell for sacks without really being hit. He limped around the field with the gait of someone who is 75 years old, not an NFL quarterback.

It was hard to watch, and you kept wondering when Zimmer would take him out. He eventually pulled the plug and inserted Case Keenum with 25 seconds left in the first half. It took entirely too long to come to that conclusion.

"I thought about it [earlier]," Zimmer said. "But he felt pretty good about things."

He certainly didn't act like it. Bradford's body language reeked of a guy who was miserable and waiting for someone to force him out of action.

Bradford completed only five of his 11 pass attempts for 36 yards. He was sacked four times, once by his own center, Pat Elflein, who got pushed into the backfield. Bradford bumped into Elflein and hit the turf. A light breeze could have knocked him over.

Bradford looked out of sorts from the opening series. His first three passes missed the mark — two on overthrows.

He then had a brain cramp that cost his team two points at the end of the first quarter. Backed up on third-and-long, Bradford dropped back in the end zone and waited and waited and waited, his internal clock clearly malfunctioning. Bradford basically gave the Bears a gift safety on a sack.

The Bears defense entered the game vulnerable, missing five starters from its opening-game lineup. The Vikings managed only 34 total yards with Bradford.

His injury makes the quarterback situation even more unsettled. He probably won't be back for some time after missing three games the first time, meaning Keenum will handle the job, for now.

Looming in the near future is Teddy Bridgewater's anticipated return from his serious knee injury, which should turn Winter Park into a soap opera set.

The Star Tribune's Ben Goessling reported Monday that the team plans to bring Bridgewater back to practice when he's eligible to come off the physically-unable-to-perform list after Week 6. That has been their plan, provided Bridgewater doesn't suffer a setback.

Under that scenario, the Vikings would have three weeks to determine whether to activate Bridgewater to the roster or keep him on the PUP list for the rest of the season.

Let's assume Bridgewater would need several weeks before he's ready to play in a game. That seems like a reasonable timetable considering his long layoff. "How's Teddy look?" will become a soundtrack played on endless loop.

Until then, Zimmer said he is hopeful that Bradford will recover again.

"We'll take everything day by day and see how it goes," he said. "But I think he's going to get back and he's going to get better."

Chip Scoggins chip.scoggins@startribune.com