SANTA CLARA -- Ahkello Witherspoon was the nearest 49ers player in coverage on a third-quarter touchdown pass to Odell Beckham that sparked the New York Giants' comeback Monday night.

And following the 49ers' 27-23 loss at Levi's Stadium, coach Kyle Shanahan expressed his disappointment in Witherspoon -- not for allowing the touchdown but for the cornerback's reaction after it.

Shanahan said Witherspoon expected help from the safety on the play. Immediately after Beckham’s TD catch, Witherspoon looked toward teammate Antone Exum and threw his hands into the air.

“Man up,” Shanahan said when asked about Witherspoon’s display of emotions. “Don’t put that on tape. We’ll deal with that when we come in.”

Veteran cornerback Richard Sherman said Witherspoon did his part on the 20-yard TD pass from quarterback Eli Manning to Beckham. Sherman blamed the score on a coverage bust in which the 49ers didn't have the correct personnel on the field.

But Sherman also said Witherspoon shouldn't have shown up his teammate on the field.

“You should never do that,” Sherman said. “That's like a cardinal rule of football. You're expecting guys to be where they're supposed to be and, unfortunately, we didn't get the personnel that we needed to on the field.”

Witherspoon denied he was upset with Exum. When asked if he expected safety help on the play, Witherspoon said, “I was expecting the ball not to be completed, and it was completed, and I was upset about it."

He added: “I was just mad at myself for allowing a touchdown. Can’t do that.”

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Witherspoon said nobody had yet spoken to him about his reaction in the immediate aftermath of the play that cut the 49ers’ lead to 20-17 in the third quarter.

“No, but I understand that,” Witherspoon said. “I know that, playing corner, I know I got to be better than that, and it’s something I got to improve on.”

Witherspoon found himself in the middle of another important play in the fourth quarter. He was called for a 16-yard pass-interference penalty against Beckham on a second-and-20 play during the Giants' game-winning drive.

When asked if he disagreed with the call, Witherspoon answered, "I did, but I also disagree with me not turning my head because I could’ve had an opportunity for an interception on that play."

It has been a difficult second season for Witherspoon, a 2017 third-round draft pick out of Colorado. He started and played well in nine starts as a rookie, but he has struggled at times this season and was benched for two starts.

Witherspoon said he has no regrets. He said this season -- ups and downs -- is all part of his journey.

"The season has been a blessing," Witherspoon said. “Every opportunity I have to play this game is an incredible opportunity for me. I’m appreciative of every single second of it. The season can’t go better than this because it’s all in God’s plan and I’m on His path and I’m doing it firmly and as a believer, so I have no complaints."