Lewis Hamilton beat Mercedes team-mate Valtteri Bottas by just 0.059 seconds to take pole position for the Spanish Grand Prix.
Neither driver improved on their final laps in an anticlimactic end to the session after Hamilton edged Bottas on the first run in the top 10 shootout.
Red Bull's Max Verstappen was third, ahead of the Racing Points of Sergio Perez and Lance Stroll.
Red Bull's Alex Albon was sixth ahead of McLaren's Carlos Sainz.
Sainz's team-mate Lando Norris was eighth. Ferrari's Charles Leclerc could manage only ninth, while team-mate Sebastian Vettel was knocked out in the second session and starts two places back in 11th.
A chance for Verstappen
Mercedes were once again in a league of their own over one lap - Verstappen was 0.708 seconds behind in qualifying, although the Dutchman showed good race pace in practice on Friday and the world champions are wary of him.
The two Mercedes drivers have been close on pace all weekend and this carried over into qualifying.
Bottas was actually faster than Hamilton over the first two sectors of their first flying laps, but the world champion had kept his tyres in good shape to put in a strong final sector.
"It's the first time we've been in Barcelona and it's this hot," he said. "Physically it's tough. The tyres are what we're really struggling with - you see us crawling around the out laps to keep temperature out the tyres but even so they get hot so quickly.
"I couldn't go quicker on my second lap. I thought I could but it wasn't a decent lap. The first was decent."
Bottas described being beaten by Hamilton in qualifying for the fourth time in six races this year as "annoying".
"It was always going to be pretty close, I knew it would be about milliseconds. Sector One and Two started to feel really good but sector three, since this morning was a bit problematic.
"Turns 10 and 12 were a bit of an issue for me in terms of balance and trying to find the best way around it."
Verstappen, winner of the last race at Silverstone on Sunday, said: "It's the maximum we can do at the moment - all weekend we have been P3. I just hope we can be a bit closer in the race.
"I just hope I can apply a bit of pressure, we will do everything we can to be close and make it difficult."
Behind the Racing Points, Albon had his best qualifying position for some time but was still more than 0.7secs slower than Verstappen, while Sainz and Norris did well to edge out Leclerc in a very tight battle.
Sainz was 0.04secs quicker than his team-mate and Norris a mere 0.003secs ahead of Leclerc.
Vettel's pace had improved after a difficult two weekends at Silverstone, but he was just over 0.2secs slower than Leclerc in the second session and missed out on the top 10 by just 0.002secs.