Stoffel Vandoorne is going for his fourth pole position in five GP2 rounds so far in 2015, but if Friday's practice is anything to go by the Belgian will be subjected to intense pressure from Rio Haryanto and Alex Lynn, both of whom were faster than the ART in their first track session of the weekend - but by the narrowest of margins.
CLICK: Full Friday GP2 practice times from Silverstone
The DAMS pair of Pierre Gasly and Alex Lynn initially took control of the timing screens but they were quickly eclipsed by improved times from Trident's Rafaelle Marciello and Sergio Canamasas - the Spaniard having relocated this weekend to Lazarus after falling out with MP Motorsport last time out in Austria, and now subbing in the #27 for the still-unwell Zoel Amberg.
Alexander Rossi was the first man to dip under 1:42 with a time of 1:41.290s in the Racing Engineering car. That put him three tenths faster than Gasly's latest improved effort with Russian Time's Mitch Evans slipping into third ahead of Marciello.
Inevitably it was only a matter of time before championship leader Stoffel Vandoorne made his bow in the top position with a time of 1:40.726s which not even an improved effort from Rossi could come close to matching. Home favourite Lynn made a better fist of things and got within 0.143s of the Belgian's fearsome early pace to go into second.
Fellow Brit Nick Yelloly was also looking on form as he slid the Hilmer Motorsports #24 car into second place. After that, and with the midpoint of the 45-minute session approaching and cars beginning to return to pit lane for set-up tweaks and new tyres, it was Campos Racing's Rio Haryanto turn to nip in front of Vandoorne with a new top time of 1:40.659s as the Indonesian driver carried through his intention to prioritise qualifying pace this weekend as the only way to stop the Vandoorne juggernaut in 2015.
Everyone continued to push hard in the second half of the session as evidenced by a lairy moment for Marciello and later by Canamasas coming out of Stowe both of whom were flirting with disaster. However, with the 3.661-mile, 18-turn circuit baking under very un-English wall-to-wall sunshine, it seemed that faster laps were vanishingly hard to come by.
Lynn was an exception to the rule and moved into second ahead of Vandoorne just three thousands of a second off Haryanto's seemingly impervious pace with a little over five minutes of practice remaining. There were no further changes in the top five after that, with Haryanto's team mate Arthur Pic finishing in sixth ahead of Gasly, Marciello, Sergey Sirotkin (Rapax) and Jordan King (Racing Engineering.)
With Status Grand Prix's Richie Stanaway in 11th place, Johnny Cecotto Jr. was 12th fasted as he returned to the series this weekend with Carlin after the team's former regular driver Marco Sorensen served notice that he would be concentrating on his GT racing duties for the rest of 2015.
Canamasas finished in 16th place just ahead of his old MP Motorsport car, which this week was taken up by Formula Renault 3.5 points leader Oliver Rowland making a one-off guest appearance in GP2. Rowland ended up having to pull off the track and park in turn 1 just after the chequered flag with an apparent technical issue, with Yelloly also suffering a similar end to his session in sector two.
Yelloly's team mate this weekend Jon Lancaster found it hard work reacclimatising to the GP2 car, and ended up 25th place on his return to the series. A former Silverstone sprint race winner, the Briton has this week taken over the second Hilmer car driven last time out by Simon Trummer.
The GP2 cars will be back out on track at 3.55pm BST for qualifying which will set the grid for Saturday afternoon's 29-lap race 1 which gets underway at 2.40pm. The shorter 21-lap sprint race will be held on Sunday morning starting at 9.35am.
The GP3 field is also in action this weekend, with practice taking place on Friday afternoon at 5.50pm and qualifying on Saturday morning at 8.45am. The 20-lap race 1 gets the green flag on Saturday afternoon at 4.20pm and the 15-lap race 2 is on Sunday morning commencing at 8.25am.
See full Friday GP2 practice times from Silverstone