Bottas must show he's got title quality: Hamilton
Lewis Hamilton has ramped up the pressure on Valtteri Bottas by challenging him to prove his Championship credentials.
Hamilton heads into tomorrow's Spanish Grand Prix trailing his team-mate by a single point.
The Mercedes pair have two victories apiece, but Bottas heads the standings by virtue of his fastest lap at the opening round in Australia.
Bottas, a winner last time out in Azerbaijan, continued his strong start by completing a practice double at Barcelona's Circuit de Catalunya yesterday.
Hamilton was just five-hundredths of a second slower, with the Ferrari duo of Charles Leclerc and Sebastian Vettel a third of a second further back, in third and fourth respectively.
Although Bottas has been quick out of the blocks, Hamilton does not traditionally come alive until the second half of the season.
Naturally, there are doubts as to whether the Finn will be able to last a 21-round campaign.
"Winning the Championship is not just about winning a couple of races," said Hamilton. "It is about the whole season. It will be interesting to see how he goes in the harder conditions. We've only had four races so watch this space."
The Mercedes hierarchy are keen that Hamilton's relationship with Bottas does not deteriorate like it did with Nico Rosberg.
Indeed, it was at this race three years ago where both Mercedes ended up in the gravel at Turn 4 after colliding on the opening lap.
In a toxic campaign, Rosberg went on to beat Hamilton to the title at the final race in Abu Dhabi. Rosberg promptly retired.
Hamilton (34) said: "I have grown a lot since then. I am much stronger in and out of the car and much better at knowing how to manage my relationships."