Liverpool manager Rafael Benitez was left fuming after seeing his Liverpool side lose ground in the Premier League with a 1-0 defeat at the Emirates stadium.
Benitez believed his side were denied a penalty when Arsenal midfielder Cesc Fabregas handled a free-kick from Steven Gerrard in the dying moments of injury time.
Referee Howard Webb waved away Liverpool's appeals and Benitez said after Wednesday night's game: "We are really disappointed with the decision of the handball. It was very, very clear. The players were on the line. It was a handball. It has to be a penalty if you see the replay."
He added: "During the game you do not realise how clear the handball was but watching the replay the referee was there.
"This year we have had some decisions that we are not very happy with. Today is another one. But you cannot complain too much because you have to be ready for the next game. You cannot waste time talking about this."
Liverpool went close through Ryan Babel, whose thunderous shot was tipped onto the bar by Arsenal goalkeeper Manuel Almunia, but they went behind in the second half when Abou Diaby headed home Tomas Rosicky's cross.
Benitez, however, believes the race for fourth place and the prized Champions League spot will go right to the end of the season.
He said: "When you lose after nine games without losing you have to be disappointed. They (Arsenal) are a good team but now we think about the future. The race for the fourth position will be to the end and we have to be ready for the next game.
"It is difficult for anyone to win too many games in a row. The main thing is to be calm and to keep going."