AP Photo SAN FRANCISCO 49ERS QUARTERBACK Jimmy Garoppolo throws against the Arizona Cardinals during the second half Thursday.

GLENDALE, Ariz. (AP) — San Francisco’s game-manager turned into quite the game-changer in an impressive performance.

Jimmy Garoppolo threw for 317 yards and four touchdowns on a night his team’s vaunted defense wasn’t at its best, and the San Francisco 49ers reached the halfway point of their season undefeated, beating the Arizona Cardinals 28-25 on Thursday.

For a quarterback who often gets the backhanded compliment of being a good game-manager, Garoppolo’s stellar performance provided some proof that the 27-year-old might be a little better than people think.

His teammates already knew.

“Yeah, he’s pretty good,” San Francisco 49ers tight end George Kittle said. “I don’t know why people don’t think he is. He makes some pretty gutsy throws out there, doesn’t he? Goodness gracious.”

San Francisco (8-0) fell behind 7-0 but responded with three touchdowns — one as time expired in the second quarter after Cardinals coach Kliff Kingsbury called a timeout and gave the 49ers a second chance on fourth down — to take a 21-7 halftime lead.

The 49ers were in control until about five minutes left in the fourth quarter, when Andy Isabella caught a short pass and sprinted for an 88-yard touchdown to help the Cardinals pull to 28-25.

But the 49ers were able to run out the clock on their ensuing offensive drive to end Arizona’s comeback. Garoppolo had two crucial third-down completions to keep the final drive alive, including one to Emmanuel Sanders who caught seven passes for 112 yards and a touchdown.

Garoppolo completed 28 of 37 throws including touchdowns of 30, 7, 1 and 21 yards.