UPDATE, 5:50 PM PT: SochiOlympicsNBC__131021180345__140123184857“We’re back now with a good opportunity to welcome in our Mary Carillo, and she’s about to bring us our nightly dose of Russian culture and no vodka tonight – please. You saw what happened last night,” Matt Lauer joked tonight as he fills in for Bob Costas on NBC‘s primetime Olympics coverage. LauerCostasHe’s referring to the previous night’s primetime coverage when Costas abandoned NBC doctors’ treatment for his ever-worsening eye infections, and went instead with vodka, telling Carillo during one of her Russian-culture segments as he downed what was billed as a good-ish dose of  the Russian booze: “My eyes can’t get any redder.” Polishing off his drink, he predicted, “Tomorrow morning I’ll be lying on a curb in Minsk.”

PREVIOUS, 4:30 PM PT: “I’m Matt Lauer, in for Bob Costas tonight. If you’ve been following along the last several days you know Bob’s been battling — and that’s an understatement — an eye infection that’s traveled a little bit,” Lauer said at the top of tonight’s NBC primetime coverage of Tuesday competition. ” I saw him in the hotel this morning — he looked a little like the loser in a prize fight.”

Walking up to the primetime coverage, NBC’s evening newscaster Brian Williams told viewers, “Bob Costas took himself out of the lineup for tonight as he deals with that eye infection,” ending a “Ripkin-like iron man streak of 157 straight primetime Olympics broadcasts that goes back to Barcelona in ’92.”

Related: NBC’s Brian Williams Newscast Attracts 16 Million Viewers From Sochi On Sunday

(WEST COAST SPOILER ALERT) All around, it’s not been a great day for NBC in Sochi. Lauer is hosting a primetime broadcast in which viewers will see a stunning Shaun White crash-and-burn during the halfpipe competition — a derailment that, because it happened hours earlier and made headlines, might keep viewers away from tonight’s broadcast. White came to Sochi hoping (as did NBC) that he would become the first American man to win three consecutive gold medals in the same Winter Games event. Since U.S. Olympics Sweetheart Lindsay Vonn pulled out of the Games due to injury, NBC had cast White as its Sochi star. White, who won the first of his two gold medals in 2006, came to Sochi in hopes of winning two more, but he pulled out of the slopestyle competition the day before qualifiers to focus on his halfpipe gold bid.

bob costasEarlier in NBC’s tough day, results for its Monday primetime tape-delayed coverage of the 2014 Winter Olympics came in: 12.8/20 national household rating and 22.4 million viewers — down 10% from the 14.2/22 ratings for the almost-live coverage from Vancouver on the comparable day in 2010 (on the Presidents Day holiday) and an 11% drop from the 25.2 million viewers.

NBC’s challenging day started earlier when Costas became the latest casualty of treacherous conditions at the Sochi Olympics, announcing on Today this morning that he’s sitting out tonight’s coverage after the infection in his left eye spread to his right. Costas had kicked off his Olympics coverage last Thursday with his left eye inflamed and sporting glasses. Five days later, Costas’ now double-eye infection had become one of the Sochi Games’ talking points — and a Twitter trending topic during last night’s broadcast. “Bob Costas appears to be having a problem with both of his eyes now,” Fox Sports reported last night.

This morning, Costas phoned in to Team Today to announce he would not host the network’s coverage tonight because his eyes had gotten even worse than last night, when they looked plenty bad enough.

“I’m walking around and I might as well be playing Marco Polo,” Costas told Lauer by phone. “I have no idea where I am.”

Later in the morning, NBC issued a news release in which Costas said he bowed out tonight because, “as a practical matter, I simply couldn’t do my job because my eyes had become so blurry, watery and sensitive to light.” He added: “I’m hopeful the symptoms will improve in the next couple of days and I can return to the broadcast. Also, the last thing I want is to go through the rest of my life owing Matt Lauer a bunch of favors.”

Said Lauer this afternoon, “I’m happy to keep his chair warm — although I might Purell it before I sit in it!”