MONTMELO, Spain - McLaren's technical troubles worsened on Saturday, while Pastor Maldonado again steered Lotus to the session's fastest lap in Formula One pre-season testing.

A faulty seal on his McLaren cut short Jenson Button's shift behind the wheel on Thursday. Two days later, the team said "similar issues" with its new Honda engine were behind the former champion registering the session's fewest laps, 24, and slowest lap.

Maldonado continued to impress by clocking the quickest lap to sit on top of the timesheet for a second time this week at the Barcelona-Catalunya Circuit, where the Venezuelan got his sole grand prix win in 2012.

Lewis Hamilton also put Mercedes in front of a revamped Ferrari for the first time this pre-season.