Former world champion Lewis Hamilton will be missed at McLaren next season, according to the team's technical director Paddy Lowe.

Speaking on the eve of this weekend's Brazilian Grand Prix title showdown, Lowe said Hamilton's speed, spectacular racing and presence in the team will be sorely felt when he joins Mercedes.

Hamilton will be making his final appearnace in McLaren colours before his transfer in this weekend's race which he has said he badly wants to win as a farewell gift to the team where he grew up and entered Formula One.

"Of course, we are going to miss Lewis a great deal," said Lowe. "He is a fantastic driver and a fantastic guy and we have been through lot of history together.

"Personally I have worked with him since 2007, but that's been six years of fantastic racing and great successes -- and some tough times as well. He is the most fantastic driver. We will all miss him.

"We wish him the best for the future and we will look forward after Brazil to next year. Things change in the world, that's how life is but we look forward to a great season next year when Sergio (Perez) arrives and there's great promise there."

Mexican Perez of Sauber has failed to score a point for his Swiss team since agreeing to leave fvor McLaren at the end of September.

Hamilton also hit a run of poor luck and results at the same time and retired while leading the Singapore and Abu Dhabi races, but bounced back with a dazzling triumph in last weekend's United States Grand Prix in Texas.

Hamilton has been backed by McLaren since the age of 11 and since his 2007 graduation into Formula One has won one world championship, in 2008, and collected 21 race triumphs.

He has also scored 49 podiums and 25 poles during his time with the team, statistics which Lowe believes underline how keenly his departure to Mercedes will be felt.

Lowe added that he hopes McLaren can pass Ferrari and take second place behind triple champions Red Bull, who clinched the 2012 title last Sunday, in the constructors' championship. McLaren are currently 12 points behind Ferrari.

"We're optimistic. There's no reason why we can't carry forward the pace we showed at the weekend in Austin into Brazil," he said.

"There's promise of rain, which will of course add a new element, but we'll be pushing very hard to win the race, not just with Lewis as Jenson is equally capable of winning in Brazil and we're going there to get two guys on the podium and hopefully on the top two steps.

"We'll admit that our prime objective is to overhaul Ferrari in the constructors. We need to get both cars ahead of Ferrari to close the gap - that's what we have to do. If there's rain it'll be even more interesting."

Team chief Martin Whitmarsh admitted earlier this week that McLaren had squandered their chances to win this year's championship because of a poor reliability record.

Lowe said: "We have had a fairly tough time in recent months with reliability and we haven't been alone with that, but the actual failures have all been things that could happen at any time.

"This car is the most reliable we have had (since 2005) -- it's just unfortunate that persistently more problems fall in races opposed to other times. For instance, we did 1500km in the young driver test without a single issue.

"It has fallen rather unfortunately for us in the races, but the car in general is reliable. We just need to keep moving ahead and next season aim for greater reliability. We know that is absolutely a key component."