However, he started the return fixture six days later and helped the Blues to an 11-9 victory at Rodney Parade.
Next up for Warburton and co is a clash with Leinster, who boast their own back-row British & Irish Lion in skipper Jamie Heaslip.
"That was a proper derby game," Warburton. "It was very close, really hotly contested at the breakdown and it's been pretty similar over the last two weeks.
"They're great games to play and the crowd was fantastic at Rodney Parade and made a lot of noise. With a lot of friends on the opposition they're great Christmas derbies to play in.
"We've got Leinster at home, which is tough, next up in ten days' time - and then into European rugby.
"But looking at the three Christmas derbies, it's two out of three wins for us, which isn't bad and something to build upon."