The England star, 31, featured for Diego Simeone's side in the 2-0 victory over Rayo Vallecano at the Wanda Metropolitano on Sunday night.
It came a day after the Magpies submitted a bid to sign Trippier within hours of the January transfer window opening.
While a fee is not yet agreed, it is understood Newcastle are confident of landing the right-back before their next Premier League fixture against Watford on January 15.
Atletico boss Simeone reluctantly admitted Trippier wants to leave, conceding it will be difficult to keep the Three Lions defender.
"We want him to stay - he's a very important player," Simeone said on Sunday.
"But nowadays, when a player wants to leave, you can't force them to stay."
Trippier certainly looked like a man set to leave at the full-time whistle following Atletico's win.
The former Tottenham right-back lingered on the pitch and gave a lengthy applause to the home crowd, before eventually joining his teammates down the tunnel.