The Football Association and PGMOL have launched investigations after an assistant referee threw an elbow at the Liverpool defender Andy Robertson during Arsenal’s thrilling 2-2 draw at Anfield. On a day of drama in the title race Arsenal squandered a two-goal lead to end six points clear of Manchester City, who have a game in hand and a home match against Mikel Arteta’s side on 26 April. But the battle for top spot was not the only talking point. Robertson said he was elbowed in the face by Constantine Hatzidakis when he approached the official after the end of the first half. Robertson, who had been warned by the referee, Paul Tierney, for haranguing Hatzidakis earlier in the game, was booked for dissent after an incident that stunned Liverpool’s players and coaching staff. Liverpool’s manager, Jürgen Klopp, declined to comment and said there had been no contact between his staff and the officials after the game. “I didn’t see it and I now have obviously time to watch it but I didn’t just because I cannot give wrong answers,” said Klopp. “I heard the pictures speak for themselves. I cannot say more. I didn’t see a bit of it.” The FA and PGMOL, the professional referees’ body, are investigating. “PGMOL is aware of an incident involving assistant referee Constantine Hatzidakis and Liverpool defender Andrew Robertson at half-time during the Liverpool v Arsenal fixture at Anfield,” read a statement. “We will review the matter in full once the game has concluded.” The same group of match officials were involved in controversy with Robertson and Liverpool last season, when the full-back was sent off and Harry Kane avoided a red card for a dangerous foul on the defender. Robertson could also be in trouble with the FA should it find that he grabbed Hatzidakis before the elbow. In a pulsating game, Gabriel Martinelli and Gabriel Jesus scored, only for Mohamed Salah to pull a goal back before half-time and miss a second-half penalty before Roberto Firmino levelled in the 87th minute. Arteta said: “When you concede at the end it always feels like two points dropped because you’re suffering in certain moments but you have it [the victory]. The feeling is: ‘We should have done it.’ But, being fair, they had four big chances to have scored late on and they missed a penalty. We have to look at ourselves in the mirror. We should have done better in the second half. “We started very well, dominated, and took the game where we wanted. When we scored the second that was the moment to kill the game but just before half-time we gave them hope. The second half was a very different story. We didn’t continue to play. We relied on big defensive moments where Aaron [Ramsdale] took a big part of it.” The Arsenal manager insisted his team would respond. “We’ve been responding for 31 games now,” he said. “Every single day is a test. The test now is how good are we going to be on Monday, and how well we prepare and play the way we want to play to beat West Ham.” Klopp described Liverpool’s comeback as another positive step, although the draw leaves his team 12 points adrift of Manchester United in the race for Champions League qualification. The Liverpool manager said: “We were part of a spectacular game because we were good for an hour. It was a great reaction. We turned the game around performance-wise and halfway results-wise. The question I had after the game was: ‘How did we not win?’ We looked better, more ready to fight back and in the second half we deserved at least a point.”