Bahrain F1 test: Hamilton leads Giovinazzi on Day 1

With the start of action having been delayed by 10 minutes so that track officials could move shipping containers away from a dangerous place at the exit of the pitlane, Hamilton's day had initially not got off to the best of starts as he brought out a red flag after just 15 minutes when his car stopped on track.

The issue was discovered to be an electrical disconnection but, once the W08 had been returned to the pits, the problem was rectified and Hamilton was able to get on with his programme.

Hamilton conducted a mixture of longer and short runs throughout the day, with Mercedes making no secret of the fact that it wants to use this week's test to better understand how to manage Pirelli's 2017 rubber.

In the end, Hamilton set his best lap of 1m31.358s on soft tyres in the final hour, meaning he ended up 0.626 seconds ahead of Ferrari test driver Antonio Giovinazzi.

While Ferrari's world championship leader Sebastian Vettel was concentrating on Pirelli's 2018 tyre test programme – which meant he was not allowed to run any development parts – Giovinazzi was tasked with the Maranello's main work for the day.

Vettel's efforts were compromised, however, by an engine problem in the afternoon which limited his running. Pirelli subsequently got agreement from other teams to extend its own private test programme until 9pm local time so it did not lose any of its hoped-for track time.

Morning pace-setter Daniel Ricciardo, who worked on aerodynamic evaluation in the morning before tyre work in the afternoon, ended up third overall.

However, his day was cut short when he suffered a Renault engine failure in the afternoon which left him stranded on track at Turn 1. A replacement power unit will be fitted overnight to allow Pierre Gasly to run on Wednesday.

"It just went," said Ricciardo. "It's sleeping at the moment. I am not sure if that one is going to wake up."

Ricciardo was not the only one to suffer a stoppage on track, with Toro Rosso rookie Sean Gelael also hitting trouble in the morning when his car ground to a halt with an electrical issue.

The Indonesian was able to get back out later in the day though, causing another red flag later in the afternoon with a fuel run-out test, before ending up eighth quickest.

Fourth fastest Romain Grosjean's main focus on the day was to evaluate new Carbone Industrie brakes, with Haas wanting to work out whether or not to make the switch from current supplier Brembo.

The Frenchman ended up ahead of Williams driver Felipe Massa and Renault's Nico Hulkenberg.

There were also engine woes for Honda, with McLaren development driver Oliver Turvey only able to complete two installation laps in the morning. Honda had discovered a water leak in the ERS, which prompted the need for a replacement power unit to be fitted.

After hours spent waiting in the garage, Turvey was able to get running again in the final hour and was able to complete 17 laps – although ended up at the bottom of the timesheets.

Pos.	Driver	Team	Time	Gap	Laps
1	Lewis Hamilton	Mercedes	1m31.358s		97
2	Antonio Giovinazzi	Ferrari	1m31.984s	0.626s	93
3	Daniel Ricciardo	Red Bull	1m32.349s	0.991s	45
4	Romain Grosjean	Haas	1m33.452s	1.094s	87
5	Felipe Massa	Williams	1m32.509s	1.151s	56
6	Nico Hulkenberg	Renault	1m33.624s	2.266s	74
7	Lance Stroll	Williams	1m33.729s	2.371s	35
8	Sean Gelael	Toro Rosso	1m33.885s	2.527s	78
9	Sebastian Vettel	Ferrari	1m33.894s	2.536s	89
10	Alfonso Celis Jr	Force India	1m33.939s	2.581s	70
11	Marcus Ericsson	Sauber	1m34.550s	3.192s	106
12	Oliver Turvey	McLaren	1m35.011s	3.653s	17