Martin and his bandmate took the stage and played Coldplay tunes Paradise and Viva La Vida.
The singer quipped, "Good evening. This is Justin Timberlake. I'm Justin Bieber. We are Bieber and Timberlake and we play Coldplay covers just for the money."
Ironically, Timberlake was sitting next to Martin's estranged wife in the audience.
Justin Timberlake and Gwyneth Paltrow. Photo / Getty Images
AmFar gala regular Sharon Stone later took the stage and complimented Paltrow for keeping her marriage split amicable.
"We thank you for your inner and outer beauty, which you demonstrated by the fact that you get along with your ex-husband (sic)."
Paltrow famously "consciously uncoupled" from her husband of 10 years in March this year but they have remained friendly and have repeatedly been photographed enjoying dinner together since the public announcement.
Martin's gala appearance occurred two days after his reported romance with actress Jennifer Lawrence came to an end following four months of dating.
- WENN