German Grand Prix, 23-25 July, Hockenheim
Coverage: Live on BBC One, Red Button, BBC Sport website and Radio 5 live
Full details of practice, qualifying and Sunday's race
Button and Hamilton happy with McLaren progress (UK users only)
By Sarah Holt
BBC Sport in Hockenheim
McLaren are confident they can challenge title rivals Red Bull for victory by reintroducing major updates at Sunday's German Grand Prix.
The updates were abandoned at Silverstone but both cars will run with them in place in practice on Friday.
McLaren driver Jenson Button said: "If we get the diffuser to work we should be quick enough to really challenge the Red Bulls for victory."
Button is second in the title race to team-mate Lewis Hamilton.
"Hopefully our package will be working and we should all be pretty close," added
rushed through their version of the exhaust blown diffuser - which increases downforce and therefore cornering speed - in Britain but took it off the cars after Friday practice, when Button described his car as "undriveable".
But after further analysis at the team's factory in Woking, the team are optimistic the update will deliver the extra performance they need to close the gap on the Red Bulls.
"It wasn't right to run the update on the car at Silverstone because it wasn't ready and we didn't have enough time to go through the whole programme with it," explained
who is 12 points off fellow Briton Hamilton's championship lead.
"But it's gone back to the factory, we'll put it on the car and hopefully we'll see the improvement. This update has to be an improvement for us round here so we can challenge for the victory.
"Red Bull have won more races than us and if they're consistent they will be very difficult to beat. It's the 11th race of the season and we have to be challenging for victories every race we go to now."
Hamilton had the fastest McLaren in Silverstone but was 0.941 seconds slower than Sebastian Vettel, who captured Red Bull's ninth pole position of the season.
The 2008 world champion had initially been keen to keep the new floor for qualifying and is confident it will now add performance at
"I felt the benefits in Silverstone but I was losing in other places so it probably balanced itself out," said Hamilton, who won the last race at the Hockenheimring in 2008.
"We're confident we've made another step forward in understanding it and trying to improve it and make it work.
The rain lashed down as the drivers arrived at Hockenheim
"I'm still not sure it's optimised. We don't expect it to be perfect this weekend but if it is working we should all be pretty close."
Red Bull have won the last two races, in Valencia and Silverstone, but trail McLaren by 29 points in the constructors' standings.
Webber, who became the only driver to win three races this season after taking Silverstone's chequered flag, is 17 points off Hamilton's lead with Vettel seven points further back.
Hockenheim's slower and tighter corners may not necessarily play to Red Bull's advantages but Webber is looking for another step-up from the team.
"We look to capitalise on some of those qualifying positions in the future," said the Australian. "There are no points given on a Saturday.
"We know that and we are looking to do better. It's not like it's a no-brainer on Sunday and we just drive off the front row and disappear.
"We have got some work to do and that is evident as you can see by the points."
Vettel finished behind Webber at the 2009 race at the Nurburgring to record his best result on home soil.
The 23-year-old is once again targeting victory but is just as keen to put an end to talk of off-track tension within Red Bull.
The team have spent the last 10 days defusing accusations of favouring Vettel when they took the new front wing off Webber's car and gave it to the German before qualifying in Silverstone.
"[There has been] a lot of talk but the most important thing you need to understand is that it doesn't matter who wins the race," Vettel added.
I'm very confident we can fight for the championship now. The car is improving race-by-race and can be on the podium regularly
Ferrari's Fernando Alonso
"In the end we are a team. We know where the focus is. It is surely on this race and nowhere else.
"The team is motivated as ever, the most important thing is the atmosphere within the team and for us it doesn't get affected by what is being said or written."
Ferrari had the fastest car compared to the Red Bull last time out and arrive in Germany with further modifications.
The team have claimed just four points in the last two races but Fernando Alonso spoke passionately about reigniting the team's title challenge.
"It's not too late," said Alonso, who slid back from fourth place after receiving a drive-through penalty in Silverstone.
"It's never too late until the last two or three races and with nine races to go there are many points on the table.
"There have been some frustrating moments in the last two races but I've very happy with the car now. I'm very confident we can fight for the championship now. The car is improving race-by-race and can be on the podium regularly."
With showers forecast for Friday practice, which begins at 0900 BST, it could be tricky for any of the teams to gauge their comparative performance.
Highlights of British GP qualifying as Button finishes in 14th (UK users only)