Barcelona twice led through Ousmane Demeble and Paco Alcacer but Iago Aspas earned Celta Vigo a deserved 2-2 draw against Ernesto Valverde's much-changed side after Sergi Roberto was sent off.
Casting an eye towards Saturday's Copa del Rey showdown against Sevilla, Valverde named an experimental line-up and started with a host of regulars, including Lionel Messi and Luis Suarez on the bench.
Somewhat expectedly, Barca lacked their usual fluency in attack and a disorganised defensive showing coughed up glorious chances to Suarez's countryman Maxi Gomez and Brais Mendez before Ousmane Dembele dispatched his maiden LaLiga goal for the visitors in the 36th minute.
Jonny Otta brought Balaidos to its feet with an equaliser in first-half stoppage time and Celta were in the ascendancy until Messi entered the fray to instantly lift the Barcelona performance.
He had no direct involvement in Alcacer's scrambled 64th-minute goal that was not enough to increase Barca's lead at the summit 14 points.
Roberto deservedly being sent off for a crude foul on the relentless Aspas did not help matters and Celta's star man was gifted his 20th goal of the season by an error from the otherwise impressive Marc-Andre ter Stegen eight minutes from time – the officials deciding not to punish the final touch coming off his arm.
Denis Suarez ceded possession in the 10th minute and was relieved to see Celta striker Gomez blast straight at Ter Stegen from Aspas's inviting cross.
Paulinho had a shot blocked behind by Jonny and the Brazil international saw his header from the resulting corner bounce back off the post.
Celta responded to that let-off by tearing forward on the break and Mendez should have put them in front from Pione Sisto's pass but curled his shot against the outside of the left upright.
Yerry Mina's sliding challenge was required to thwart Gomez after Barca's makeshift midfield was picked apart, while Ter Stegen – captain for the evening – clawed Mendez's 34th-minute attempt away from the top corner.
As such, Barca's opener came again the run of play when Alcacer improvised well, having slightly lost his footing, to chip the ball into Dembele's path for the winger to lash home.
Jonny made a crucial challenge to prevent Paulinho from making it 2-0, meaning the left-back was a fitting recipient of Gomez's low cross to equalise with the final kick of the half.
Messi and Roberto replaced Coutinho and Andre Gomes with half an hour to play, embarking upon contrasting substitute appearances.
The mercurial Argentinian immediately orchestrated a mesmerising move, with Lucas Digne tamely prodding the ball into Alvarez's gloves an unsatisfactory conclusion.
Digne's fellow full-back Nelson Semedo made a more incisive contribution in the 64th minute – Paulinho bundling his excellent cross beyond Alvarez before Alcacer got the faintest of touches to claim the goal.
Aspas led the charge for a second Celta equaliser and thumped narrowly wide to Ter Stegen's left.
The Spain forward was then hauled back by Roberto as he scampered through on goal, leaving referee David Jose Fernandez Borbalan with little option but to brandish the red card.
Aspas fired just over from the free-kick but would not be denied, forcing the ball home when Ter Stegen failed to deal with substitute Emre Mor's excellent cross.
A combination of Ter Stegen and Digne intervened when another substitute Lucas Boye looked set to net the winner but Barca's record-breaking run moves onto 40 games, just.