Bottas could have won the Azerbaijan Grand Prix but for a puncture three laps from the end while leading. File photo: Luca Bruno / AP

Barcelona, Spain - With three second places from five races, Valtteri Bottas believes he is hitting his targets for the Formula One season even if victory has so far escaped him.

Bottas, Mercedes team-mate to four-times world champion Lewis Hamilton, would have been a winner in Azerbaijan in April but for suffering a puncture three laps from the end while leading.

In Spain on Sunday he followed race winner Hamilton in the team's first one-two finish of the campaign, albeit 22 seconds adrift on very worn tyres after a marathon 47 lap stint on a single set.

Bottas, whose future beyond 2018 remains uncertain, told reporters after Sunday's race: "I think this year I've been meeting more or less my targets with the performance for the beginning of the year.

"I think I've been able to really continue good performance since the very end of last year. There's been no weekends that I've been really way off the pace, like there was a few last year. So I think I've learned from those; I just need to continue my development, there's never things that you can't learn more."

Uneven debut season

Bottas won the 2017 season-ending Abu Dhabi Grand Prix, after an uneven first year at Mercedes following his move from Williams to replace retired 2016 world champion Nico Rosberg. Hamilton won nine races to Bottas's three in 2017.

Bottas started 2018 with a crash in qualifying in Australia, collecting a five place grid penalty for an unscheduled gearbox change that left him 15th on the grid.

He finished eighth, then bounced back by outqualifying Hamilton in Bahrain and China, finishing second in both races, and was runner-up again on Sunday in a race the champion dominated. Had he not drawn a blank in Baku, Bottas would be a lot closer to Hamilton than the current 37 points.

He has had some criticism too, with Red Bull's Daniel Ricciardo - among those most likely to replace him - saying after Bahrain that he would have tried to pass Ferrari's race winner Sebastian Vettel rather than settling for second.

But Bottas said: "I think there's been quite mixed races and the end results haven't been really I feel sometimes quite there, that I feel would have been possible with the pace we have. The gap to Lewis was huge at Catalunya but there were many things that affected that."