Artur Janosz set the pace on the opening day of the second GP3 pre-season test at Valencia, putting Trident on top of the timesheets.
The Polish driver, who is entering his sophomore GP3 season, clocked his best time of 1m21.755s in the final half-hour of morning session, dethroning Jenzer's recent signing Oscar Tunjo.
Alex Albon and Konstantin Tereshchenko were two tenths off in second and third with their late flyers, displacing Charles Leclerc.
Tunjo was just 0.012s adrift the Ferrari protege in fifth, while the Monegasque had Jack Aitken, Alex Palou, Nyck de Vries and Tatiana Calderon less than a tenth behind as well.
Koiranen's Matt Parry was quickest in the afternoon after beating long-time leader Jake Dennis to the spot.
The duo were two of the few drivers able to improve their morning times, Parry becoming second quickest overall.
Aitken made up an all-British top three, just two hundredths slower than his teammate Dennis.
Nirei Fukuzumi was fourth, leading ART teammates Leclerc and Albon.
|2||Matt Parry||Koiranen GP||1:22.241||1:21.932|
|3||Alex Albon||ART Grand Prix||1:21.954||1:22.411|
|4||Konstantin Tereshchenko||Campos Racing||1:21.976||1:22.885|
|5||Charles Leclerc||ART Grand Prix||1:22.017||1:22.295|
|6||Oscar Tunjo||Jenzer Motorsport||1:22.029||1:22.433|
|7||Jack Aitken||Arden International||1:22.054||1:22.188|
|8||Alex Palou||Campos Racing||1:22.076||1:22.925|
|9||Nyck de Vries||ART Grand Prix||1:22.096||1:22.535|
|10||Tatiana Calderon||Arden International||1:22.112||1:22.916|
|11||Jake Dennis||Arden International||1:22.377||1:22.161|
|13||Ralph Boschung||Koiranen GP||1:22.199||1:22.565|
|14||Nirei Fukuzumi||ART Grand Prix||1:22.232||1:22.286|
|15||Steijn Schothorst||Campos Racing||1:22.317||1:22.435|
|19||Matevos Isaakyan||Koiranen GP||1:22.470||1:22.527|
|22||Richard Gonda||Jenzer Motorsport||1:23.098||1:22.734|
|23||Akash Nandy||Jenzer Motorsport||1:22.798||1:23.166|
|24||Mahaveer Raghunathan||Koiranen GP||1:23.285||1:23.061|