Force India had rivals wondering whether they could be the next Formula One team to spring a surprise after rocketing up the timesheets in Friday's free practice for the European Grand Prix.
Germany's Nico Hulkenberg was second fastest in the afternoon session, just 0.131 off the pace set by Red Bull's double world champion Sebastian Vettel, while Britain's Paul Di Resta was sixth.
"Sometimes a car suits one track better than it suits another. You might see something different again this weekend," McLaren's championship leader Lewis Hamilton told reporters after the session.
"Force India looks massively quick this week so who knows what is going to happen...the Force India was unbelievably quick today. I don't know where they found their time."
His team mate Jenson Button agreed that their rivals, whose car has the same Mercedes engine as the McLaren, appeared to have found a sweet spot.
"Force India is extremely quick. We haven't seen that really all year so it seems like somebody else is having their opportunity this weekend," said the 2009 champion.
"They are sort of the team that has been almost competitive but not quite there but here they seem to be very competitive."
Silverstone-based Force India had hoped to make a big step up this year and have made one of their best starts in terms of points scored but have also been left behind by mid-table rivals they had hoped to be ahead of.
The season has been particularly unpredictable, with seven different winners in seven races including Williams' Venezuelan Pastor Maldonado while Force India are still waiting to get one of their drivers on the podium.
Team principal Vijay Mallya said before Valencia, the eighth round of the championship, that he wanted the team to raise their game and the drivers were confident that had happened.
"Our single lap speed looks strong, as does the long run pace, and we appear to have a good feel for the tyres already," said Di Resta.
"Given the pace we have shown today we seem competitive so hopefully we can challenge for the top 10 in qualifying tomorrow."