Anchorman Brian Williams will be undergoing knee surgery and taking a leave of absence from Nightly News.

EOnline reports that the 54 year-old anchor announced his absence during Thursday night's program. He said, "If you don't see me around here for a while, this is the reason why."

Williams will go under the knife to reverse a high school football injury. According to USAToday he will replace his cartilage. The multi-decade injury has been causing him intense pains that keep him up at night.

It is unsure what effect his absence will have on the show's ratings. Bloomburg Businessweek reports that the news program showed a rare drop in ratings last week. The Nielsen company said ABC's World News beat NBC among the 25- to 54-year-old demographic, putting an end to 243 consecutive weeks of NBC's winning streak.

Lester Holt will replace Williams on Nightly News during his absence. It has not been determined how long his break will be.

Image courtesy of NBCUniversal