Bob Costas has had to call in sick a third day at SochiNBC Sports tweeted this morning that Costas, who’d been missing from the past two nbcsochi__131202172913days of Olympics broadcasts owing to a nasty case of pinkeye, will sit out tonight’s primetime coverage. Once again, NBC News’ Matt Lauer will step in. “I’m hoping that I’m back by the weekend and I certainly think I’ll be able to do the second half of the games,” Costas told Ryan Seacrest on his radio program this morning, adding, “The virus, they tell me, won’t run its course for two or three weeks, but the symptoms will crest at their worst and start to get better pretty soon. As soon as the symptoms get to the point where I can be in the studio, I’ll be there.” Seacrest, like Costas, is part of NBCU-parent Comcast’s family — hence the interview going to Seacrest. Comcast calls it “symphony.”

MattLauerCostas, NBC‘s primetime and late-night Olympics anchor, has been absent from NBC’s Games broadcasts since Tuesday, when his Twitter-trending swollen pink eyes forced him into what he called “involuntary” absence. Costas, via telephone, explained on NBC’s Today show his eyes had become so “blurry and watery…and so light sensitive” even dim light caused them to start weeping, making it impossible for him to work in the studio.

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In return for the fill-in, Costas promised Lauer he’d fill in for him on the next 10 segments of Today show segments Steals and Deals, and Ambush Makeovers.

Costas showed up last Thursday to anchor early Games coverage, sporting a badly swollen left eye, glasses, and an apology to viewers. Tuesday’s stand-down ended Costas’ uninterrupted run as anchor of NBC’s Olympics broadcasts since the late 1980s.