Tottenham midfielder Dele Alli was struck on the head by a bottle at Arsenal while helping his team seal a place in the League Cup semifinals with a 2-0 victory in the north London derby on Wednesday.
The plastic bottle was hurled from the stands at the Emirates Stadium about 12 minutes after Alli audaciously lobbed goalkeeper Petr Cech as Tottenham won at its rival for the first time since 2010.
"It made the goal a little bit sweeter and the win," said Alli, who responded by using his fingers to signal Tottenham's 2-0 lead to the Arsenal fans.
Police in helmets were also brought into the stands to provide a larger barrier between Tottenham and Arsenal fans.
The supporter who threw the bottle faces a ban if he is identified from video footage.
"It's lucky it wasn't a big issue," Tottenham manager Mauricio Pochettino said. "Only one stupid person made a mistake."
Having also ousted West Ham in the previous round, another London team stands in the way of Tottenham reaching the final. There will be a two-legged meeting in January with Chelsea, which beat Bournemouth 1-0 on Wednesday on Eden Hazard's goal.
Holder Manchester City was drawn to play third-tier side Burton.
For Tottenham manager Mauricio Pochettino, the lack of trophy is the only blot on a reign that began in 2014. But the progress he has made with meager spending compared with the rest of the Premier League's top four has made the Argentine a prime target as Jose Mourinho's long-term successor at Manchester United.
Both goals were set up by a compatriot of Pochettino, with goalkeeper Paulo Gazzaniga launching high balls.
The first in the 20th minute reached Alli who picked out Son Heung-Min to slot past Cech as Arsenal had nothing to show for its opening command of the quarterfinal.
Having been rested from kickoff, Harry Kane made a swift impact from the bench by setting up the second goal. Gazzaniga sent the ball in the 59th minute to Kane, who held it up on the halfway before directing a cross-field pass to Alli for the exquisite dink over Cech.
Winning at Arsenal allowed Tottenham to exact quick revenge for a loss in their Premier League meeting almost three weeks ago.
Coupled with the loss on Sunday to Southampton, Arsenal has now endured back-to-back defeats after a 22-match unbeaten run.
While one route for silverware ended in Unai Emery's first season at Arsenal, Tottenham remains in contention on four fronts -- like City and Chelsea. Tottenham's FA Cup run starts in January in the third round at Tranmere, there is a Champions League last-16 meeting with Borussia Dortmund and Pochettino's side is third in the Premier League.