It's day two of the first in season test in Barcelona at the Circuit de Catalunya, and Mercedes' Valtteri Bottas sits at the top of the timesheets as it stands.
The Finn, fresh from his second place finish in the Spanish GP on Sunday, has completed 33 laps with a best time of 1:17:187.
With the exception of McLaren and Force India, each team has only run one car so far today.
It is difficult to read too much into this session so far, for the top teams anyway, with the Ferrari being driven by Antonio Giovinazzi and Jake Dennis driving the Red Bull.
Jake Dennis is joined by fellow British drivers Jack Aitken and Lando Norris, of Renault and McLaren respectively.
Giovinazzi sits in P2 but is over 1.6 seconds behind leader Bottas.
There are more positive signs for Sauber and Charles Leclerc, off the back of two consecutive points finishes.
The Monegasque driver sits third, ahead of both Kevin Magnussen and Stoffel Vandoorne, and has also competed more laps than both.
Elsewhere, Robert Kubica is going well in the Williams, completing 25 laps so far.