Rui Vitoria was forced to accept a point from Benfica's Group B opener in the Champions League after a familiar face secured Besiktas a dramatic 1-1 draw.
The Portuguese club were on course for victory thanks to Franco Cervi's 12th-minute goal, only for a free-kick from Anderson Talisca - who is on loan from the hosts - to draw Besiktas level in stoppage time.
Vitoria watched the stunning equaliser from the stands while serving a touchline ban following his dismissal against Bayern Munich in the quarter-final second-leg defeat last season.
"The team is working well, we practically won the game. But this is the Champions League," he told the club's website.
"We need to improve on details. A late goal is hard to take in.
"We faced the Turkish champions, they have excellent players. We couldn't get three points here, so we need to find them somewhere else."
Talisca, who only moved to Turkey last month, sent a 30-yard free-kick into the bottom corner of the net to silence the majority of the crowd inside the Estadio da Luz on Tuesday.
"Talisca's goal was an unfortunate moment for us. We were careful, controlling the match. It was unlucky," Vitoria added.
Benfica's next European fixture sees them travel to Italy to take on Napoli.