A qualifying style run in the afternoon netted Pastor Maldonado his second P1 at this week's Barcelona test.
The Lotus driver, whose team have swapped to Mercedes power for this year's Championship, put in a spate of short runs on the super-soft tyres on Saturday afternoon.
Maldonado clocked a 1:24.384 on his one-flying lap run to take the P1 slot ahead of Max Verstappen.
The Toro Rosso driver was another to use the super-soft tyres to achieve his lap time and he finished 0.391s off the pace.
It was a solid showing from the rookie but ended with his STR10 parked jjust after the pit lane exit.
Verstappen, along with Jenson Button, brought out the day's final red as both drivers broke down within moments of one another and both on the pit lane exit.
It was Button's second red flag of the day, the first caused one again by a faulty seal on his McLaren-Honda's MGU-K which is again having to be redesigned.
Third place went to Lewis Hamilton, whose 1:26.340 was posted on the medium tyres while Marcus Ericsson claimed fourth place.
It was a troubled start to the day for the Swedish racer and his Sauber team who spent the morning fixing the C34's gearbox. Ericsson only emerged 30 minutes before the lunch break.
Sebastian Vettel, who brought out the day's first red when he spun off on cold tyres just two minutes into the morning, was fifth quickest ahead od Daniil Kvyat.
Felipe Massa was seventh on a day when Williams focused mainly on pit stop practices. He handed the FW37 over to Valtteri Bottas in the afternoon with the Finn ninth quickest.
The duo were separated by Pascal Wehrlein while Button was slowest of all with just 24 laps to his tally.
01 Pastor Maldonado Lotus 1:24.348 104 laps
02 Max Verstappen Toro Rosso 1:24.739 0.391 129 laps
03 Lewis Hamilton Mercedes 1:26.076 1.728 101 laps
04 Marcus Ericsson Sauber 1:26.340 1.992 52 laps
05 Sebastian Vettel Ferrari 1:26.407 2.059 105 laps
06 Daniil Kvyat Red Bull 1:26.589 2.241 110 laps
07 Felipe Massa Williams 1:26.912 2.564 55 laps
08 Pascal Wehrlein Force India 1:27.333 2.985 81 laps
09 Valtteri Bottas Williams 1:27.556 3.208 48 laps
10 Jenson Button McLaren 1:29.151 4.803 24 laps