The pair were nominated by fellow model Georgia Salpa, who was saved from eviction by the public against Andrew Stone moments earlier.
Salpa was called into the Diary Room after the results were announced, and was asked to choose two celebrities to face the viewer vote while the other housemates watched on the TV screen.
She was told that the other housemates would be "punished" if she refused to nominate.
An upset Salpa eventually chose McLean and Giggs, saying: "That was really hard because I love everybody."
Evicted housemate Stone agreed with Salpa's choices, telling host Brian Dowling: "I would have chosen the same two."
Celebrity Big Brother continues tomorrow at 9pm on Channel 5.
> Natalie Cassidy has already won Celeb Big Brother, says Dean Gaffney
Watch Natasha Giggs and Nicola McLean being put up for eviction by Georgia Salpa below: