The issues returned in the afternoon, but this time with a hydraulic failure on the Belgian's 38th lap of the test, stopping his auto in turn three.
"It was a good day's work", said Vettel after completing 171 laps, the most of any of the 13 drivers who took to the track.
Ricciardo had the most laps among all drivers with 165.
"I think it will be all three of us against each other". "On the tyres, if you look at the lap time, Red Bull did a test this morning, [they] put on new mediums [and then] new softs".
"It's obviously not the productive day we had planned, but the problems. are the types of niggles that we nearly hope and expect to face during testing, in order to prepare us properly for the season ahead".
Alonso did 47 laps in the morning before stopping out on track after just over two hours of the day's running.More news: Jurors shown blast footage as commuters fled Parsons Green Tube train
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Alonso has played down the lack of running McLaren has experienced during pre-season testing, after Stoffel Vandoorne suffered two battery issues and a hydraulics failure yesterday, and feels his team has the fundamentals in place ahead of the 2018 opening race. "It's obviously not the productive day we had planned, but the problems - a battery issue and a hydraulic leak - are the types of niggles that we nearly hope and expect to face during testing". "On the tyre story - as I said last week, and it's still the same - we have a technical reason why we want to work on the vehicle with these tyres".
Bell said of Tuesday's issues: "Those problems could have affected any of the three teams, so of course it's an issue for us". Reigning world champions Mercedes surpassed that over the day, albeit by splitting duties between Lewis Hamilton and Valtteri Bottas for a combined 172, although Renault led the way with the 190 completed by Carlos Sainz and Nico Hulkenberg.
He was fourth-fastest with a 1:19.541 lap set on soft tyres.
"What we have seen from Red Bull is that they have a very strong package", added the Austrian, whose Mercedes team are going for their fifth drivers' and constructors' championship double in a row.
Behind Vettel came Brendon Hartley, who improved late on a mixed day in which he had a spin and a stoppage at the pitlane exit but still completed 118 laps.
"I still don't really know where Ferrari is, I'm quite confident Mercedes is still just maybe in front of us".