Newcastle boss Eddie Howe said the "pain you feel now is motivation for tomorrow" after their Champions League exit following a 2-1 loss to AC Milan.
The Magpies were on course to go through between Joelinton's 33rd-minute opener and Christian Pulisic's 59th-minute equaliser at St James' Park.
Samuel Chukwueze's winner six minutes from time denied Newcastle the consolation of a Europa League spot.
"I'm desperately disappointed. It's tough to take," said Howe.
Newcastle qualified for the Champions League for the first time since 2002-03 by finishing fourth in the Premier League last season.