The 49ers' defense, overall, played well against Kansas City Chiefs quarterback Patrick Mahomes.

However, San Francisco ultimately was unable to stop Mahomes and the Kansas City offense when it mattered most, resulting in an ugly 28-18 loss on Sunday at Levi's Stadium.

Mahomes completed 16 of 27 pass attempts (59 percent) for 154 passing yards with zero touchdown passes and two interceptions while rushing five times for 39 rushing yards and a touchdown on the ground.

His 44.4 passer rating on Sunday, according to the 49ers' game notes, was his worst in any game throughout his eight-year NFL career and the lowest by an opposing quarterback against San Francisco's defense in five years.

· The 49ers defense held Kansas City Chiefs QB Patrick Mahomes to a passer rating of 44.4 on the day, marking the lowest single-game passer rating of his career.

· Mahomes' 44.4 passer rating marked the lowest single-game passer rating by an opposing QB since the 49ers defense held former Panthers QB Kyle Allen to a passer rating of 28.9 vs. Car. (10/27/19).

Despite his struggles, Mahomes came up big when the Chiefs needed him most, allowing Kansas City's offense to take advantage of 49ers quarterback Brock Purdy's mistakes.

Purdy's day wasn't much better. The third-year 49ers quarterback completed 17 of 31 pass attempts (54 percent) for 212 passing yards and three interceptions while rushing eight times for 27 yards and two scores on the ground.

While the 49ers' defense played well on Sunday, recording two takeaways and forcing an early turnover on downs, Purdy and the 49ers' offense couldn't do much with their opportunities.

Meanwhile, Mahomes and the Chiefs' offense did just enough.