Lionel Messi pressured referee in tunnel at half-time of Clasico - Sergio Ramos

Sergio Ramos believes Clasico referee Alejandro Jose Hernandez Hernandez gave in to pressure put on him by Lionel Messi as Barcelona and Real Madrid played out a thrilling 2-2 draw on Sunday.

Hernandez Hernandez angered Camp Nou supporters in a fiery first half for failing to punish Gareth Bale for a late challenge on Samuel Umtiti and sending off Sergi Roberto following a clash with Marcelo.

Barca players crowded around Hernandez Hernandez at the end of the first 45 minutes, and the home fans jeered him and his assistants off the pitch. Ramos said the dispute continued down the tunnel, with Messi at the centre of the complaining.

"Messi put a little bit of pressure [on Hernandez Hernandez] in the tunnel," Ramos told reporters after the game. "I don't know if there were cameras. I don't know if in the second half [he] would have done things differently [without that pressure]."

Luis Suarez's early opener was cancelled out by Cristiano Ronaldo, who was later taken off with an ankle injury, to leave the score level at the break. Despite being down to 10 men, Barca took the lead when Messi scored after Suarez dispossessed Raphael Varane.

Bale drew Madrid level for the second time, and the visitors were then denied a penalty when Marcelo tumbled in the box, one of the decisions that Ramos perhaps feels Messi influenced.

The other one was Suarez's challenge on Varane before Messi's goal, with the Uruguayan striker admitting that he was surprised a foul wasn't called after he clearly tripped the France international.

"I fouled Varane a little bit because he controls the ball and I catch his foot," Suarez admitted. "But it was the referee's decision. It surprised me."

Ramos also felt that Suarez was guilty of time wasting in the second half, which is why he didn't put the ball out when the Barca forward appeared to be down injured.

"Whenever an opponent is down and you think it could [be] serious, out of respect, you put the ball out of play," Ramos said. "But knowing his style and his way of playing, he was [looking] to waste time. Maximum respect to Barcelona, but at that moment, he had not been touched at all."

Overall, though, both sets of players were happy with the draw, which keeps La Liga champions Barca on track to become the first side to go through a 38-game campaign in Spain's top flight unbeaten.

"It was a great game," Suarez said. "We wanted to win it, but the red card set us back, especially against a side like Madrid. A draw's not a bad result, mind, considering how the game went."

Midfielder Andres Iniesta, making his 38th and final Clasico appearance, added: "We're still unbeaten after playing a large part of the game with a man less. That's the positive. We're happy because we can still end the league season without losing."

Barca, who have already secured a domestic double, must remain unbeaten against Villarreal, Levante and Real Sociedad to become the first side since Madrid (in 1932, when a campaign was only 18 games) to end a La Liga season unbeaten.

Madrid, meanwhile, are preparing for a third consecutive Champions League final. They meet Liverpool in Kiev, Ukraine, later this month.

"It was a good game to show that we wanted to win the league. We played really well, generally, from the first minute to the last," Ramos said. "We got a draw. We would have liked to break [Barcelona's] run, but preparing for Kiev is the key now."