La Liga have been criticised for not having video review assistance.
Barcelona reached 35 points from 13 matches, eight points ahead of Atletico Madrid and Real Madrid, who both won.
Valencia had won nine straight in all competitions, with their last setback a 1-1 draw at Levante in September.
It was an even match at the packed Mestalla, with Barcelona playing better in the first half and the hosts threatening the most in the second.
"After the goal we had opportunities to put the game away, but in the end I think it was a fair result," Rodrigo said.
Valencia went ahead after Jose Gaya made a run through the left side of the area and sent a low cross for Rodrigo. He beat keeper Marc-Andre ter Stegen to the ball and tapped it in.
Alba equalised with a left-footed shot into the far corner after Messi's well-placed pass over the defenders.
Earlier, Sevilla came back from 2-0 down to beat Villarreal 3-2 away to sit fifth, behind fourth-placed Real Madrid and Atletico Madrid (third).
Deportivo La Coruna and Athletic Bilbao drew 2-2 at the Riazor, and Las Palmas moved off the bottom by ending an eight-game losing run with a 2-2 draw at Real Sociedad.
• Napoli moved back to the top of Italy's Serie A with a 1-0 win at Udinese yesterday.
Jorginho scored the only goal after his penalty had been saved, to send Napoli two points above Inter Milan, who won 3-1 at Cagliari.
Third-placed Juventus beat Crotone 3-0 later to cut the gap to Napoli back to four points. Fullback Mattia De Sciglio unleashed a powerful strike in the win.
It was his first goal as a professional in a combined 173 matches for AC Milan, Juventus and Italy's national team.
Roma were denied their 13th successive away league win after veteran midfielder Daniele De Rossi gave away a needless penalty and was sent off in a 1-1 draw at Genoa.
Roma were leading 1-0 in a bad-tempered match when De Rossi became involved in an off-the-ball pushing match with Genoa forward Gianluca Lapadula and slapped his opponent's face. The referee awarded a penalty which Lapadula converted in the 70th minute and the 34-year-old De Rossi was sent off.
- Agencies