Lionel Messi had a legitimate goal controversially denied as La Liga leaders Barcelona hit back to snatch a 1-1 draw at second-placed Valencia.
Messi's tame first-half strike squirmed through the grasp of Valencia goalkeeper Neto and over the line at Mestalla but it was not spotted by the officials and, with the absence of goal-line technology in Spain, play was allowed to continue.
In-form Valencia took advantage of their fortune when Rodrigo slotted them into a 60th-minute lead but Jordi Alba equalised against his former club with a late volley to keep Barca four points ahead of their rivals.
During an uneventful start to the match, Barcelona's Brazilian midfielder Paulinho had a long-range shot tipped over by Neto before the keeper comfortably saved from Ivan Rakitic minutes later.
Barca began to dominate possession, leading to the game's major talking point with half an hour played.
Messi was picked out by Luis Suarez on the edge of the box and the Argentinian's seemingly harmless side-footed shot slipped through the hands and then the legs of Brazilian Neto before clearly crossing the goal-line.
Unfortunately for the visitors, the assistant referee had not kept up with play and the game was allowed to continue by match official Ignacio Iglesias Villanueva.
Messi was clearly incensed with the decision and he almost had more reason to be unhappy moments later as Valencia instantly broke down the other end and in-form Italy striker Simone Zaza fired a powerful strike just off target.
Following prolonged speculation, Messi committed his future to Barcelona on Saturday and he continued in search of a goal to celebrate the new three-and-half-year contract by striking a 30-yard free-kick which Neto kept out at the base of the right post.
Valencia had not beaten Barcelona in the league at Mestalla for more than a decade and they remained on the back foot for the duration of the first period.
Suarez almost broke the deadlock three minutes prior to the interval when he held off the attentions of Jose Luis Gaya before his low shot was repelled by the legs of Neto and Messi's follow-up was blocked.
The game began to open up after the restart and, after Zaza struck another attempt off target, Valencia's Paris St Germain loanee Goncalo Guedes wriggled past Samuel Umtiti before his attempted pull-back was smothered by visiting Barca goalkeeper Marc-Andre ter Stegen.
After enjoying 71 per cent first-half possession, the visitors fell behind on the hour mark.
Portuguese midfielder Guedes played in full-back Gaya and his dangerous ball across the box was turned in by Rodrigo.
Former Bolton loanee Rodrigo celebrated in bizarre fashion by putting on a red wig taken from the crowd but he was not to be the match-winner as, moments after he was replaced by Andreas Pereira, Barca levelled.
The ever-dangerous Messi found space in the centre of the pitch to dink a delightful ball into the path of Alba and he expertly smashed home with eight minutes remaining to leave both sides unbeaten.