Romain Grosjean says it will only take 'one update going in the right way' for Lotus to get on terms with Williams in its battle to progress beyond the mid-field.

With its disastrous 2014 season firmly behind it, Lotus has shown flashes of good form during the opening four races of the season, Grosjean picking up seventh place finishes in China and Bahrain.

With the E23 proving a clear top ten contender, unlike its 2014 predecessor which struggled for points, Lotus is turning its attentions on closing the gap to the teams directly ahead, namely Red Bull and Williams, with a raft of updates due for the upcoming Spanish Grand Prix.

Suggesting Williams is currently half a second faster than Lotus at this time, Grosjean says it would only take one update to work in its favour to start getting on terms with the British team.

"We've been to different tracks in Melbourne, Kuala Lumpur and China, all with different limitations and the behaviour of the car is always the same so that's very positive in a way we can focus on those areas. We have a bigger update for Barcelona and until you test it on track you don't know but from the wind tunnel and everything it should be going in the right direction."

"Williams are probably 0.5s quicker than we are right now which seems to be a lot and not much at the same time. Sometimes it just takes one update going in the right direction to take it. That's probably something we'll know by Barcelona if we've been in a good direction or not."