Arsenal boss Arsene Wenger was angry with the decision to send off Aaron Ramsey as his side drew at Besiktas in their Champions League play-off.
Ramsey was dismissed after twice being cautioned for pulling back Besiktas players and will now miss the second leg at Emirates Stadium on 27 August.
The player later took to Twitter to tell fans: "Sorry for the the red card."
"Neither the first nor the second yellow card was deserved," said Wenger.
"When you see some of the fouls that were made and we go home with Ramsey sent off, it is a bit unbelievable."
Arsenal's hopes of reaching the lucrative group stages of the Champions League for the 17th successive season are in the balance after an open game in Istanbul ended goalless.
Ramsey, who scored a stoppage-time winner against Crystal Palace in the Gunners' first Premier League game of the season on Saturday, was sent off with 11 minutes to go.
|Arsenal's record in Champions League qualifiers|
|Arsenal had won all 12 of their previous Champions League qualifying games, scoring 29 goals and conceding only three, while keeping nine clean sheets. They beat Fenerbahce 3-0 in the first leg of their play-off last season, again in Istanbul, going on to win 5-0 on aggregate.|
He was shown a second yellow card for tugging on former Arsenal midfielder Oguzhan Ozyakup's shirt after losing possession near the halfway line.
The dismissal was Ramsey's first in senior club football, although he was sent off playing for Wales in a World Cup qualifier against Scotland in 2013.
And Wenger was furious with Serbian referee Milorad Mazic, who also sent Besiktas boss Slaven Bilic to the stands in injury time.
"In the second half the performance of the referee was very bad," Wenger said. "Ramsey's second yellow card, I cannot see where that came from, it was a huge decision.
"I felt a lot was wrong in the second half but, overall, it was a difficult game maybe to referee as well because everybody did fight for every ball."
Wenger said Besiktas had stretched his side with their fast attacking play but, even though Ramsey will be suspended, he is confident of winning the second leg next week.
"It was a difficult match, played at a high pace," Wenger added. "Besiktas played with 100% pace in the game and fought for every single ball, and it was quick. We needed a great level of concentration.
"We always want to win but look, Besiktas could have won the game, and we could have won the game as well. Maybe a draw is a fair result because both teams had chances to win the game.
"We know the second leg will be certainly tight again, but we are at home, so the task is clear for us, we want to win."
Wenger also confirmed he had reported to Uefa that an object had been thrown at him as he left the pitch at full-time at the Ataturk Olympic Stadium.