Having broken the lap record in the opening test session of the second day at Aragon, Red Bull junior Carlos Sainz then went on to post the quickest time of the afternoon.
Yet again, the Spanish youngster was largely not in the fight for the top spot until the closing minutes of the session, with Arden teammates Will Buller and Pierre Gasly taking on the leading role. The Frenchman maintained his hold at the top spot throughout much of the running, but would be deposed by his squadmate with less than 15 minutes to go.
However, the Brit would not retain first for long, as a last-minute series of laps from Sainz allowed him to firmly secure the lead in the session. The Red Bull youngster would eventually wind up with a time that was two tenths off of his lap record, but still allowed him to retain the top spot.
Sauber test driver Sergey Sirotkin was 0.25s adrift in second, while Gasly settled for third.
Pietro Fantin continued an impressive run of testing pace with fourth, leading the British duo of Will Buller and Caterham Academy driver Will Stevens.
Nigel Melker ended his first day of testing with Tech 1 in seventh, ahead of Sainz’s teammate Norman Nato, with Jazeman Jaafar narrowly beating Marlon Stockinger to ninth.
The Aragon test will conclude with two more sessions on Thursday.
|2||Sergey Sirotkin||Fortec Motorsports||1:38.798||0.254||20|
|3||Pierre Gasly||Arden Motorsport||1:38.859||0.315||31|
|4||Pietro Fantin||International Draco Racing||1:38.864||0.320||23|
|5||Will Buller||Arden Motorsport||1:38.994||0.450||33|
|6||Will Stevens||Strakka Racing||1:39.030||0.486||29|
|7||Nigel Melker||Tech 1 Racing||1:39.144||0.600||31|
|11||Luca Ghiotto||International Draco Racing||1:39.249||0.705||24|
|13||Marco Sorensen||Tech 1 Racing||1:39.467||0.923||28|
|14||Tom Dillmann||Pons Racing||1:39.499||0.955||24|
|16||Matias Laine||Strakka Racing||1:39.859||1.315||30|
|17||Nikolay Martsenko||Comtec Racing||1:40.229||1.685||13|
|18||Meindert van Buuren||Pons Racing||1:40.256||1.712||28|
|19||Roberto Merhi||Zeta Corse||1:40.498||1.954||26|
|20||Roman Mavlanov||Zeta Corse||1:40.596||2.052||20|
|22||Liam Venter||Comtec Racing||1:41.187||2.643||19|
|23||Oliver Rowland||Fortec Motorsports||1:47.706||9.162||17|