BARCELONA, Spain -- Mercedes' domination of the Circuit de Catalunya continued into the first day of this week's in-season test in Spain as Valtteri Bottas topped the timesheets by 1.711s.
The two-day test, taking place at the scene of Mercedes' one-two victory at Sunday's Spanish Grand Prix, is the last chance for the teams to take part in unrestricted testing this season. All ten teams are present and the focus was split between gathering data on test parts and preparation for the next round in Monaco.
Bottas' fastest time appeared to be a result of the latter as Mercedes bolted on Pirelli's softest compound -- the C5 -- which is due to make its race debut in Monaco. The time, a 1:15.511, was just over a tenth of a second slower than Bottas' pole position time on Saturday, which he set using the C3, a compound two steps harder.
"We've had a number of developments on the chassis and power unit side which we can hopefully bring to the race car over the next few races," chief engineer Andrew Shovlin said. "We've also done some work on setup for the softer compounds that will be appearing in Monaco and Montreal, along with some longer run work."
Ferrari ran two cars at the test -- one to gather data on the SF90 and one to develop Pirelli's 2020 tyres -- with Charles Leclerc setting the second fastest time by the end of the day. The team's focus is on trying to understand why it was losing so much time to Mercedes in the corners and Leclerc's fastest lap, a 1:17.222, was set on the C2 compound -- the tyre designated as the medium over the grand prix weekend.
The session was suspended twice by red flags, one when Pierre Gasly's Red Bull stopped on track with a transmission issue in the afternoon and one when Ferrari junior driver Calum Ilott crashed heavily at Turn 3 in the Alfa Romeo.
Ilott's incident was not caught on camera, but Turn 3 is one of the fastest corners on the circuit and the resulting damage brought an end to his session. The British driver walked away from the wreckage but images of the Alfa Romeo returning to the pits showed significant damage to the left hand-side of the car. Alfa Romeo was still looking into the exact cause after the session, but Ilott, who was making is F1 debut on Tuesday, felt he should take the majority of the blame.
"It just completely snapped on me," he said. "It was out of nowhere and then I backed into the wall. It was probably the biggest off I've ever had -- so a record breaker for me on my first day in F1!
"Obviously, not good at all but I can only look at the positives from the day when it ends like that. But it's really unfortunate. I don't want to be so negative about it. It was my first day in F1 and we did have some really positive steps in the day before that -- with little to no mistakes before. I was really getting comfortable and this was a weird anomaly that happened on the fastest corner on the circuit."
"If anything you blame me more than anything else. I want to find out what caused it, whether it was an environment thing or if I was slightly off line, but there was nothing obvious at the moment. So it was either circumstantial that with that wind on that lap it just goes, but we are still looking."
Other non-F1 drivers taking part in Tuesday's test included Pietro Fittipaldi -- the grandson of two-time champion Emerson -- in the Haas, Blancpain GT driver Nick Yelloly in the Racing Point and F2 championship leader Nicholas Latifi in the Williams.
The test continues on Wednesday with both Mercedes and Ferrari set to hand their cars over to young, non-F1 drivers. Russian F2 driver Nikita Mazepin will drive the Mercedes as part of his role as a simulator driver and to complement the private tests he is completing in a 2017 Mercedes F1 car this year.
Ferrari junior driver Antonio Fuoco will take over the Italian team's test car on Wednesday while Leclerc switches to the Pirelli car that was driven by Sebastian Vettel on Tuesday.
1. Valtteri Bottas (Mercedes) - 1m15.511s - C5 compound - 131 laps
2. Charles Leclerc (Ferrari) - 1m16.933s - C2 compound - 131 laps
3. Daniil Kvyat (Toro Rosso) - 1m17.679s - C4 compound - 121 laps
4. Nico Hulkenberg (Renault) - 1m18.051s - C3 compound - 68 laps
5. Pierre Gasly (Red Bull) - 1m18.140s - C3 compound - 118 laps
6. Carlos Sainz (McLaren) - 1m18.263s - C2 compound - 64 laps
7. Pietro Fittipaldi (Haas) - 1m18.326s - PROTO compound - 103 laps
8. Nick Yelloly (Racing Point) - 1m18.361s - C5 compound - 111 laps
9. Lando Norris (McLaren) - 1m18.567s - C3 compound - 44 laps
10. Callum Ilott (Alfa Romeo) - 1m19.819s - C2 compound - 41 laps
11. Nicholas Latifi (Williams) - 1m20.670s - C2 compound - 133 laps
Pirelli tyre test:
Sebastian Vettel (Ferrari) - 1:18.425 - 132 laps
Sergio Perez (Force India) - 1:19.719 - 118 laps