McLaren are back in the title fight after emerging from a spell of poor results, team chief Martin Whitmarsh said today.

He said he believed that the team now has the car and a strong enough development programme to fight for the world championship.

After disappointing results in the European and British Grands Prix, McLaren returned to form on Sunday when Briton Jenson Button finished second in the German Grand Prix.

The result followed the introduction of a major package of upgrades for the car, including modified sidepods and exhausts.

In dry conditions, the McLaren was the fastest car racing round the Hockenheim circuit.

"It is good enough at the moment," said Whitmarsh, referring to the revived car.

"But it won't be, if we don't keep developing it, because we have half a season to go.

"Both of our drivers are capable of winning races and this year's world championship. The onus is on us to keep developing.

"We have a reasonable amount of momentum in the system at the moment. From what I have seen, that was the opinion of our engineers too. So we are feeling optimistic."

While Button got a boost on Sunday from a penalty handed to defending champion German Sebastian Vettel, who ran off the track in passing him in the final stages of the race, his team-mate and fellow-Briton Lewis Hamilton had to retire for the second time in three races following a puncture and other problems.

Whitmarsh refused to rule out either driver or the team making up a big points deficit to revive their challenge in the championship.

In the constructors' championship, McLaren are in third place, 70 points behind Red Bull, while Lewis Hamilton and Jenson Button are 62 and 86 points off drivers' championship leader Fernando Alonso, who won Sunday after leading from start to finish.

"Fernando is doing a great job and so is Ferrari, but we are fighters so there will be some great races and we need to maximise our points," Whitmarsh said.

"In Germany, we could catch him and hurt our tyres, but we couldn't get past him. We were a reasonable amount quicker, but if you put someone like Fernando at the front of a race then you are going to have difficulty getting past him."

As Whitmarsh voiced optimism, rival team chief Eric Boullier of Lotus said he was confident his team can fight back and beat McLaren to take third place in the teams' title fight.

McLaren moved into third in the constructors' championship thanks to Button's second place ahead of Finn Kimi Raikkonen of Lotus.

Both their respective team-mates Hamilton and Frenchman Romain Grosjean failed to score.

Lotus are now one point behind McLaren.

Boullier said: "It's obviously disappointing to lose third place, but it's very, very tight and we've built a gap over the fifth-placed team.

"We are hungry for success and we do want more. If we can keep bringing the developments and updates we have been planning and make them work on track then I think we should be able to defend our current position."

He added that he was aware that Lotus needed to improve their qualifying form to bring any success.

Raikkonen qualified in 10th in Germany while Grosjean started from 19th.

"It's clear what we need to do for better results. Anyone who watches Formula One can tell us this. We need to do better in qualifying," Boullier said.

"It's clear that if we want to win races we have to be top four or five on the grid."