Silverstone, Northamptonshire - Lewis Hamilton was fastest in practice for his home British Grand Prix on Friday despite losing precious track time due to a Mercedes engine problem.
Hamilton, who has not won at Silverstone since 2008 but desperately needs to do so on Sunday to rein in runaway team-mate and Formula One championship leader Nico Rosberg, set a best time of 1m34.508s on a blustery day.
However, Hamilton had to sit out the last half hour after an oil pressure problem stopped him on track with 30 minutes remaining.
That meant the 2008 champion, who is 29 points adrift of Rosberg after eight races, did only 14 laps after lunch compared to Rosberg's 35 and was unable to complete an important long run race simulation.
Rosberg ended the day second fastest, 0.228sec off Hamilton's pace in the afternoon.
”I don't know why it happens to my car so much.”
"It happens. I don't really know what the car feels like for the race but I will try to get some long runs tomorrow,” said Hamilton, who has suffered two race retirements this season.
Hamilton will be able to study Rosberg's data but he said that would not help much because of their different styles.
"It's OK, I'll be all right," he added.
Rosberg was quickest in a morning session notable for the presence of a woman driver, Susie Wolff, for the first time in 22 years.Hamilton is determined to regain the championship momentum after being beaten by his team-mate in the previous three Grands Prix, although he has won four races to Rosberg's three so far.
Ferrari's Fernando Alonso was third on the timesheets in both sessions with Red Bull's Australian Daniel Ricciardo fourth.
Red Bull's four times champion Sebastian Vettel was fifth in the afternoon.
Wolff suffered considerably more frustration than Hamilton after her involvement in the opening session, at the wheel of the car to be raced by Valtteri Bottas on Sunday, lasted barely 20 minutes.
She managed just four laps before an oil pressure problem forced her to park at the side of the circuit on a sunny but breezy morning at Silverstone.
Even if that ended her track activities, Wolff was still the first woman to take part in any stage of a grand prix weekend since Italian Giovanna Amati tried and failed to qualify with Brabham in 1992.
Italian Lella Lombardi, in 1976, was the last woman to race in Formula One.
Wolff said later: "It was a really tough day but that's Formula One sometimes. We had an oil pressure problem that cut the engine.
"Once I put the helmet on that was the best feeling, and as soon as I had left the pit lane, everything felt good. Unfortunately it was a short run but I'm going to look forward to Hockenheim," added Wolff, who will have a second run at the German Grand Prix later in July.
On a bad morning for Williams, which finished third and fourth in Austria two weeks before, Felipe Massa then brought out the red flags after a heavy crash that also ruled him out of the rest of the morning.
Massa spun and hit the wall hard near the exit to Stowe corner with little more than an hour of practice remaining, bringing the session to a halt. He was unhurt in the impact but the car suffered heavy damage.
"I'm fine. I hit the outside of the kerb and it just pushed me inside," said the former Ferrari driver, who will be starting his 200th race this weekend but first at Silverstone with a British team.
RESULTS – SECOND SESSION
1 Lewis Hamilton (Britain) Mercedes – 1m34.508s
2 Nico Rosberg (Germany) Mercedes - 1:34.736
3 Fernando Alonso (Spain) Ferrari - 1:35.244
4 Daniel Ricciardo (Australia) Red Bull - 1:35.511
5 Sebastian Vettel (Germany) Red Bull - 1:35.627
6 Valtteri Bottas (Finland) Williams - 1:36.016
7 Jenson Button (Britain) McLaren - 1:36.228
8 Kevin Magnussen (Denmark) McLaren - 1:36.299
9 Kimi Raikkonen (Finland) Ferrari - 1:36.554
10 Jean-Eric Vergne (France) Toro Rosso - 1:36.583
11 Felipe Massa (Brazil) Williams - 1:36.671
12 Daniil Kvyat (Russia) Toro Rosso - 1:36.778
13 Esteban Gutierrez (Mexico) Sauber - 1:36.951
14 Pastor Maldonado (Venezuela) Lotus - 1:37.064
15 Romain Grosjean (France) Lotus - 1:37.097
16 Sergio Perez (Mexico) Force India - 1:37.236
17 Nico Huelkenberg (Germany) Force India - 1:37.449
18 Adrian Sutil (Germany) Sauber - 1:37.520
19 Jules Bianchi (France) Marussia - 1:38.658
20 Kamui Kobayashi (Japan) Caterham - 1:39.068
21 Max Chilton (Britain) Marussia - 1:39.224
22 Marcus Ericsson (Sweden) Caterham - 1:39.762
RESULTS - FIRST SESSION
1 Nico Rosberg (Germany) Mercedes - 1m35.424s
2 Lewis Hamilton (Britain) Mercedes - 1:36.155
3. Fernando Alonso (Spain) Ferrari - 1:36.263
4 Daniel Ricciardo (Australia) Red Bull - 1:36.623
5 Kimi Raikkonen (Finland) Ferrari - 1:36.703
6 Sebastian Vettel (Germany) Red Bull - 1:36.921
7 Jenson Button (Britain) McLaren - 1:36.963
8 Daniil Kvyat (Russia) Toro Rosso - 1:37.175
9 Jean-Eric Vergne (France) Toro Rosso - 1:37.227
10 Kevin Magnussen (Denmark) McLaren - 1:37.231
11 Sergio Perez (Mexico) Force India - 1:37.720
12 Romain Grosjean (France) Lotus - 1:37.910
13 Esteban Gutierrez (Mexico) Sauber - 1:38.056
14 Daniel Juncadella (Spain) Force India - 1:38.083
15 Giedo van der Garde (Netherlands) Sauber - 1:38.328
16 Jules Bianchi (France) Marussia - 1:38.917
17 Felipe Massa (Brazil) Williams - 1:39.461
18 Max Chilton (Britain) Marussia - 1:39.814
19 Marcus Ericsson (Sweden) Caterham - 1:40.597
20 Robin Frijns (Netherlands) Caterham - 1:42.261
21 Susie Wolff (Britain) Williams - 1:44.212
22 Pastor Maldonado (Venezuela) Lotus