A brawl allegedly broke out in the tunnel after Atletico Madrid secured a last-gasp point against Unai Emery's Villarreal on Sunday.

Villarreal looked to be heading for an unlikely victory when new signing Arnaut Danjuma restored their lead in the 74th minute after Luis Suarez had cancelled out Manu Trigueros' opening strike earlier in the second half.

But in the fifth minute of stoppage time Atletico's Saul Niguez sent a hopeful ball upfield and Algerian defender Mandi rose to head it back towards goalkeeper Geronimo Rulli, instead glancing into his own net to the horror of his team mates.

And reports claim things quickly turned sour following the final whistle.

Referee Soto Grado reported that the two teams clashed in the tunnel, with both players and coaches involved.

Spanish outlet AS say his report revealed that Atletico coach Pedro Tomas Renones Crego 'hit a member of the visiting coaching staff' while Emery's assistant Villarreal Imanol Idiakez confronted Atletico players and staff 'aggressively and had to be held by members of his team.'

There are also claims a coach was punched in the mouth.

While Villarreal could hardly believe their misfortune, a draw was no less than Atletico deserved after firing 23 shots at goal to the visitors' two, both of which ended up in the net.

The late drama avoided a first home defeat for Atletico since February and moved them to seven points after three games alongside five other teams, with Real Madrid leading the standings on goal difference.

Atletico had dominated the first half but went behind against the run of play early in the second period to a thumping strike from midfielder Trigueros from just inside the area following a lay off from Yeremi Pino.

Luis Suarez scored his first goal of the season to pull the hosts level soon after, expertly slotting in a pass from Angel Correa, who had scored Atletico's previous three goals this season in victories over Celta Vigo and Elche.

But the Uruguayan, whose 21 goals in the last campaign were crucial to Atletico landing the title, later went off injured and was seen on the bench nursing his knee with a pack of ice.

Villarreal went ahead again after a mix up between Atleti defenders Stefan Savic and Jose Gimenez, leaving Dutch forward Danjuma, who was making his first start since a reported 25 million euro ($29.49 million) switch from Bournemouth, to pounce on the loose ball and lift it past goalkeeper Jan Oblak.

The home side pressed for an equaliser and Rulli did well to push a shot from Koke over the bar.

But he was left flummoxed by Mandi's header and Atletico could hardly believe their luck, coach Diego Simeone celebrating wildly on the sidelines with his substitutes and coaching staff.

The own goal was a cruel twist for Villarreal coach Unai Emery, who has still never enjoyed a victory over Simeone after 11 matches.