Ahead of today's opening session the air temperature is 16 degrees C, while the track temperature is 41 degrees. It is bright and sunny, albeit a little cool.
In terms of updates, McLaren has a new Front Wing, Rear Wing and Front Suspension. The revised geometry on the front wing is aimed at improving aerodynamic performance across a wide range of attitudes, through a redesign of main elements as well as introduction of 'mermaid tails' to the front wing endplate. The updated version of the medium downforce rear wing assembly enables a more efficient coverage of a larger drag range, suitable for multiple circuits. Finally, there's a small modification to the front suspension geometry which comes with an updated aerodynamic surface, to accommodate the geometry change and re-optimize local flow conditioning.
Mercedes has a new Floor Corner and Floor Edge. The front corner sees an increased front brake duct inlet and exit area to cover off high brake duty for this circuit, while reduced flap chord and tweaked vanes, increase mass flow under the forward floor and vorticity shed from the fence system, increasing floor load.
Aston Martin has a new Front Corner. The larger exit area for the front brake duct increases the mass flow through the front corner increasing cooling for the characteristics of this circuit.
Alpine has a new Front Wing on which the flap has been shortened and redesigned, generating less load, therefore offering the aero-balance range that may be required for the track characteristics.
RB has a new Front Wing and Rear Corner. At lower rear wing levels, the car must be balanced with reduced front downforce. The reduced-chord flap allows the aerodynamic balance to be lowered beyond the minimum range achievable by the previous flap. It achieves this by reducing the load generated by the front wing at a given flap angle. In terms of the rear corner, the vorticity shed from the brake drum winglet helps to manage the airflow around the tyre and the diffuser. This update improves the quality and consistency of the shed vortex, which in turn increases rear downforce.
These are the only updates this weekend.
Having withdrawn from the Barcelona race, Stroll is back in the Aston Martin, albeit looking extremely surly, if yesterday's press conference is anything to go by.
The lights go green and Ocon leads the way, followed by Piastri, Hulkenberg, Hamilton and Colapinto. As more drivers head out it's a mixture of mediums and softs.
There are a lot of aero rakes in use, along with flo-vis, while a couple of the teams that have brought upgrades are running back-to-back tests.
There's an early spin for Colapinto as he begins his first flying lap.
Hamilton posts a benchmark 17.018, and while Verstappen responds with a 16.067, the Dutchman reports that his steering is very heavy.
Having monitored his car Verstappen is told to stay out as there doesn't appear to be an obvious issue.
No sooner has Leclerc posted a 15.848 than Hadjar crosses the line at 15.419.
Albon goes quickest with a 15.148 ahead of Tsunoda (15.195).
A 14.478 from Verstappen as he goes quickest in all three sectors.
"I just locked the rears," reports Antonelli as he runs wide.
Quickest in the first two sectors, Norris goes fifth with a 15.081. On successive laps the McLaren driver locks up at the hairpin.
Leclerc improves with a 13.885 as Piastri remains the only driver yet to post a time.
Russell goes second (14.031), ahead of Norris, Verstappen and Hadjar.
Oh dear, Leclerc is off and in the barrier at Turn 4. Replay shows he overcooked it into Turn 3, hit the barrier on the left with his front wheel and then careered into the barrier opposite. He has done damage to the front and rear of the car.
"****, I'm in the wall, my bad," he reports as the session is red-flagged. "I went straight on, I didn't make it and hit the wall."
Replay shows another near miss when Bortoleto had to take avoiding action as he came across a slow Albon who was seeking to avoid an even slower Ferrari.
The session resumes and Russell leads the way, followed by Piastri, Norris, Ocon and Bearman.
Piastri, on his first flying lap of the day, goes fourteenth with a 15.604.
As ever, the track is very dusty, hence the offs continue, with Norris and Russell taking to the grass, while Hamilton does a 360 at the hairpin.
An awkward moment in the Ferrari garage as Piero Ferrari steadfastly looks at the monitors as behind him Leclerc explains his mistake.
Piastri improves to eleventh with a 14.578.
A 13.535 sees Russell go top as Hulkenberg brushes the Wall of Champions with his right-rear.
Verstappen improves with a 13.863, albeit 0.328s off Russell's pace.
With just over 20 minutes remaining, all bar Lawson are on softs.
Tsunoda improves to fifth while Gasly goes sixth.
A 13.275 puts Sainz top but he is immediately leapfrogged by Verstappen and his 13.193.
"****, not giving a lot of space," says Verstappen of Hamilton who has just gone fourth with a 13.620.
Albon goes second with a 13.232, this being a track that plays to the Williams' strengths.
Alonso goes eighth with a 13.972, while teammate Mr Personality remains nineteenth.
Alonso is critical of Albon's antics, particularly at Turn 2. The Williams driver has been noted for impeding the Aston Martin driver.
Hadjar goes sixth with a 13.671, while Lawson goes ninth (13.960).
Gasly improves to seventh.
The right-hand side of Norris's car is smothered in flo-vis as the evaluations continue.
Attention switches to Sunday and the opening phase of the race with high fuel.
That said, Norris improves to seventh with a 13.651. Previously the Briton got wildly out of shape in Turn 10.
As the clock counts down, Bortoleto and Lawson are the only drivers on mediums, the softs having been the go-to tyre for the entire session.
The session ends. Verstappen is quickest, ahead of Albon, Sainz, Russell, Hamilton, Hadjar, Norris, Lawson, Gasly and Leclerc.
Tsunoda is eleventh, ahead of Alonso, Antonelli, Piastri, Stroll, Bortoleto, Bearman, Ocon, Colapinto and Hulkenberg.
Check out our Friday gallery from Montreal here.
sign in