Football: Messi penalty snatches thrilling Barca win

However, the dramatic victory came at a cost for Barca as a tearful Andres Iniesta suffered ligament damage in his right knee that could keep him out for several months.

Messi netted twice and his opener midway through the first half was allowed to stand despite Luis Suarez straying into an offside position.

Valencia hit back with two goals in six second-half minutes through on-loan Barca winger Munir El Haddadi and Rodrigo.

However, Suarez levelled and was then upended inside the area by Aymen Abdennour to allow Messi to hold his nerve and slot past penalty-stopping specialist Diego Alves for all three points.

Victory moves the champions a point clear of Atletico Madrid and Real Madrid, who face Sevilla and Athletic Bilbao respectively on Sunday.

He may be one of the finest footballers ever but Messi has struggled from the spot in recent seasons, most notably blazing over as Argentina lost the Copa America final to Chile in June.

"Our best penalty-taker is Leo Messi without any doubt," Barca boss Luis Enrique said.

Valencia stopper Alves had saved three penalties this season and from Messi in the past, but was beaten low to his right.

"Messi took responsibility in the best moment and it is a glorious feeling for us," added Enrique.

A bad-tempered encounter spilled over after Messi's strike, though, as Suarez and Neymar were hit by a plastic bottle thrown by the Valencia fans as Barca celebrated.

"We celebrated as it is normal to celebrate a last-minute winner," said Enrique.

- 'Absolutely lamentable' - The game was only 14 minutes old when Iniesta was carried from the field in tears holding his right knee, which buckled under a heavy challenge from Enzo Perez.

Enrique was furious with referee Alberto Undiano Mallenco as Perez avoided even a yellow card, whilst a series of other fouls on Barca players went unpunished.

Barca confirmed Iniesta suffered lateral collateral ligament damage, but said further tests would be carried out to determine the exact extent of the injury.

However, it was Valencia who were up in arms at the officials when Messi opened the scoring on 22 minutes.

The Argentine's fifth goal in three games since returning from a groin injury sneaked in at Alves's near post, but the Brazilian goalkeeper had been distracted by the presence of the offside Suarez jumping over Messi's effort.

"It is lamentable, absolutely lamentable that refereeing decisions prevented Valencia from taking a point or more from this match," Valencia sporting director Jesus Garcia Pitarch told BeIN Sports Spain.

Valencia turned the game around early in the second half as Dani Parejo's cut-back was drilled into the bottom corner by El Haddadi against his parent club.

The 21-year-old held his hands up apologetically after finding the net, but there were wild celebrations led by new Valencia boss Cesare Prandelli moments later when Rodrigo swept home Nani's through ball.

Valencia's lead lasted just six minutes despite Alves's best efforts as Suarez pounced to smash home a rebound after Ivan Rakitic's powerful header had been saved by the Valencia stopper.

Barca swarmed forward in search of a winner, but had to wait until deep into stoppage time when Messi played in Suarez and he was clearly taken out from behind by Abdennour.

Messi stroked home his 14th goal of the season to secure a vital three points in the title race.

Earlier, Espanyol battled back from 3-0 down at half-time to salvage a point and possibly coach Quique Sanchez Flores's job in a 3-3 draw at home to Eibar.