Lionel Messi tormented Celta Vigo and Ansu Fati scored his third goal in two LaLiga games as 10-man Barcelona secured a 3-0 victory in horrendous conditions at Balaidos.
Fati followed up his double in a 4-0 rout of Villarreal on Sunday by scoring the opening goal on Thursday before Barca defender Clement Lenglet was harshly sent off for a second bookable offence late in the first half.
Celta were unable to capitalise on their numerical advantage and Lucas Olaza's own goal, created by the mercurial Messi, gave Ronald Koeman's side breathing space.
Messi also had a goal disallowed for offside when he looked to be level, but the Blaugrana were not to be denied another three points in the wind and rain and Sergi Roberto added the final flourish in stoppage time as they won at Celta for the first time since 2015.
Barca knocked the ball around with a swagger following their demolition of Villarreal and were in front after 11 minutes when Fati took a first-time pass from Philippe Coutinho and poked home with the outside of his right foot.
Lenglet was cautioned for upending Gabri Veiga, who had a shot palmed away by Neto, and Barca breathed a sigh of relief when Gerard Pique's red card for a professional foul on Denis Suarez was overturned with the midfielder offside.
Pique's fellow defender Lenglet was given his marching orders three minutes before the break, though, when Carlos del Cerro Grande harshly adjudged him to have impeded former Barca man Suarez for a second yellow.
Koeman reacted by replacing Antoine Griezmann with Ronald Araujo, but the Blaugrana doubled their lead five minutes after the break, thanks in no small part to Messi.
The captain darted away from two challenges and Olaza could only turn the Argentina forward's right-footed cross into his own net as the rain continued to hammer down.
Messi looked to have added a third but was given offside when he turned in the rebound after Coutinho struck the post and Pique was unable to convert a dangerous cross from his outstanding skipper.
Miguel Baeza saw his deflected effort strike the crossbar on a frustrating night for Celta as Barca showed great spirit and quality to make it two wins out of two in LaLiga, with Roberto putting the icing on the cake by drilling in a third right at the end.
What does it mean? Crisis, what crisis?
There had been talk of a crisis at Barca after Messi asked to leave in August, before agreeing to stay on for the 2020-21 season. But Messi's commitment was there to be seen once again as he produced yet another brilliant performance, which deserved at least one goal.
He showed predatory instincts to pounce when Coutinho was denied by the woodwork, only to see the flag up, and saw his shot saved before Roberto fired in with time almost up. Messi made 60 successful passes, with an accuracy of 92.3 per cent, and also put Celta under pressure with six crosses.
Coutinho pulls the strings
Brazil playmaker Coutinho was also a constant menace to Celta, causing all sorts of problems as he drifted into space and pulled the strings.
The former Liverpool man was also thought to be heading out of the club, having returned from a loan spell with Bayern Munich, but on this evidence could be a key man.
His sharp pass gave Fati the chance to open the scoring and Coutinho came a whisker away from getting on the scoresheet himself when his right-footed drive came back off the post.
Misery for Lenglet and Griezmann
Lenglet was sent off for the fourth time in all competitions since signing for the Catalan giants, more than any other player since the 2018-19 season.
Having signed right-back Sergino Dest from Ajax earlier in the day, Koeman will surely now be eager to bring in another centre-back, with Eric Garcia still reportedly a target.
Lenglet's early departure also brought Griezmann's participation to an early end, the France forward having struggled to make the sort of impact the likes of Messi, Coutinho and Fati did.
Barca return to Camp Nou for a mouthwatering clash with Sevilla on Sunday, while Celta visit Osasuna