Button's F1 future uncertain as McLaren waits on Alonso, Vettel

Should McLaren pull off a coup and land one of its targets, then it will have to decide which of its current drivers will be dropped.

Although Button has world-championship winning credentials and was previously thought to be a no-brainer to keep on, team-mate Kevin Magnussen's form recently has impressed and the team may feel he is a better prospect longer term.

Racing director Eric Boullier admitted that situation was not clear cut, but said having to make such a hard choice would be a good problem to have as it would mean it has captured a big star.

When asked if Magnussen's strong run of form against Button was making life harder when it came to making a decision for 2015, Boullier said: "We are not at that point yet - but I hope he will make my life difficult.

"We need to think what is best for the team. It is part of the strategy that we may have over the next three to five years, so it is something we have to take into consideration."

The chances of McLaren getting hold of Vettel or Alonso for 2015 are very slim, which makes it likely that Button and Magnussen will be handed short-term deals.

However, until it knows its longer term plans, Button and Magnussen are being forced to wait and neither has even a firm offer for next year.

When asked if his drivers were happy to wait for the outcome of the Vettel/Alonso talks, Boullier said: "No. Everybody wants to know what they want to do next season and as early as possible.

"I understand this, but people need to understand as well that we went through a transition period.

"Ron [Dennis] is back, and I joined the team, and obviously there is a change that is being done so it is a rebuilding process."