Chelsea are keen to get Romelu Lukaku back from Everton, which could see Diego Costa head out the door.

For the fourth and final day of the opening pre season Formula One testing session here at the Barcelona Circuit in Spain it was the Ferrari of Kimi Raikkonen at the top of the timesheets, the Finn almost a second quicker than second placed man, Red Bull Racing's Max Verstappen.

Meanwhile, RenaultF1's Jolyon Palmer was a pleasing third quickest ahead of Romain Grosjean in the Haas.

“We have learnt a lot over the course of this first test. It has been rewarding for the team to work with Nico for the first time in the car and both him and Jolyon have given us positive feedback regarding the R.S.17," said Renault's  Managing Director Cyril Abiteboul.

"Our teams back at Enstone and Viry-Châtillon have worked tremendously hard to produce the R.S.17 and we have seen the first glimpse of its potential this week. Our engineers have made strong progress over the past four days and we are confident that we will continue to do so over the course of the next test too."

The circuit was artificially soaked for a wet Pirelli tyre testing day and the teams made the most of the wet track while they had the chance.

For the first time this week, Mercedes failed to have a trouble free day with Lewis Hamilton having issues in the morning session that forced the three time champion out of the action for the entire morning session.

Testing will resume again here next week.

Times from day four:
1. Kimi Raikkonen Ferrari 1:20.872s 93 laps
2. Max Verstappen Red Bull Racing 1:21.769s 85 laps
3. Jolyon Palmer Renault 1:21.778s 39 laps
4. Romain Grosjean Haas 1:22.309s 118 laps
5. Antonio Giovinazzi Sauber 1:22.401s 84 laps
6. Sergio Perez Force India 1:22.534s 82 laps
7. Stoffel Vandoorne McLaren-Honda 1:22.576s 67 laps
8. Valtteri Bottas Mercedes 1:23.443s 68 laps
9. Nico Hulkenberg Renault 1:24.974s 51 laps
10. Daniil Kvyat Toro Rosso 1 lap