Meredith Vieira replacing Bob Costas as television host Friday

With no end in sight to Bob Costas’ eye ailment, NBC is digging deeper into its bench for its Friday broadcast from Sochi.

The network’s public relations staff tweeted that Meredith Vieira will host the primetime and late-night Olympic coverage on Friday as Costas continues to deal with the eye infection that has hampered him since the Sochi Games began.

The decision apparently makes Vieira the first woman to work as a solo host for an Olympic primetime telecast on a US network. Matt Lauer filled in for Costas Tuesday through Thursday while also anchoring the Today show each morning.

Vieira, who used to co-host the Today show with Lauer and will return to the network this fall on a talk show, covered the Opening Ceremony from Sochi last Friday and has been reporting this week from local venues.

NBC did not say when Costas might be able to resume working.