Hamilton improved the mark slightly to 1m23.931s in the second session. Picture: Brandon Malone / Reuters

Melbourne, Australia - Champion Lewis Hamilton topped the timesheets for Mercedes in both practice sessions at the Formula One season-opening Australian Grand Prix on Friday but Red Bull's Max Verstappen showed enough pace to give the Silver Arrows pause for thought.

After lapping Albert Park in 1m24.026s during the first session, Hamilton improved the mark slightly to 1m23.931s in the second session on a balmy autumn day.

Red Bull's Dutch wunderkind Verstappen was snapping at Hamilton's heels, however, and finished only 0.127s adrift of the four-times champion after FP2.

Verstappen sandwiched himself between the Mercedes drivers, with Hamilton's team-mate Valtteri Bottas third quickest despite taking a couple of slides off the circuit.

Ferrari's Kimi Raikkonen was fourth in FP2 but will have to face the stewards after Bottas nearly rammed into his rear and ended up in the gravel.

It was a less encouraging day for Ferrari's four-times champion Sebastian Vettel, who was more than half a second off the pace in FP2, finishing fifth, while Red Bull's home hope Daniel Ricciardo battled to seventh.

There will be a buzz around the Haas garage, however, as Romain Grosjean was sixth quickest in FP2 and his team-mate Kevin Magnussen ninth.

After battling an exhaust system problem for much of FP1, Renault-powered McLaren showed encouraging signs with former double world champion Fernando Alonso eventually lapping eighth and holding the position in the later session.

Canadian Lance Stroll's day ended in frustration, with his Williams forced to a halt at the end of FP2 with overheating issues. He was 14th for the session, ahead of his debutant team mate Sergey Sirotkin in 18th.