By Abhishek Takle

BUDAPEST (Reuters) - Lewis Hamilton got his bid for a record fifth Hungarian Formula One Grand Prix win off to a strong start by going fastest for Mercedes in the opening practice session for Sunday's race.

The reigning triple champion, hoping to seize the championship lead for the first time this season, lapped the 4.3-kilometer long Hungaroring track in one minute 21.347 seconds in a session that in overcast conditions but ended in bright sunshine.

Nico Rosberg, fresh from having signed a two-year contract extension keeping him at Mercedes until the end of 2018, was second with a lap of one minute 21.584.

Rosberg, winner of five races this year, heads to the weekend holding a slim one-point lead over Hamilton, down from the 43-point advantage he held over the Briton after the Spanish Grand Prix in May.

Hamilton has bounced back from a difficult start to the season with four wins from the last five races and heads into Sunday’s race as favorite to seize the championship lead.

He has won four times at the Hungaroring, jointly holding the record for most wins at the track with Michael Schumacher, and another victory would be more than anyone has ever managed here.

Sebastian Vettel, winner in Hungary last year, was third for Ferrari ahead of team-mate Kimi Raikkonen. Both scarlet cars were over a second-and-a-half slower than Hamilton’s benchmark.

Daniel Ricciardo, another former winner at the Hungaroring, led Red Bull’s charge in fifth ahead of 18-year-old team-mate Max Verstappen.

The former champions, who have made big strides in recent races, are hoping to mount a genuine challenge to Mercedes this weekend.

McLaren, who are also expecting an improvement in form, were seventh and eighth with Fernando Alonso ahead of Jenson Button, on a track where both claimed their maiden Formula One wins.

Romain Grosjean’s Haas and the Force India of Sergio Perez rounded out the top 10.

Mercedes-backed Esteban Ocon, who also doubles up as Renault’s reserve driver, drove Kevin Magnussen’s car for the French team and ended the session 18th.

The 90-minute session was largely incident free with a few harmless spins as well as some drivers running wide to test the new track-limits monitoring system being introduced this weekend by the sport’s governing body.

(Editing by Amlan Chakraborty)