Officially: Mercedes is signing Alonso. Conditions of the contract

Mercedes are thinking about signing McLaren driver Fernando Alonso to replace Nico Rosberg, team boss Toto Wolff says.

A move would reunite Alonso and Lewis Hamilton, who had a stormy partnership at McLaren in 2007.

Rosberg, 31, retired five days after winning the Formula 1 world title.

"You have to consider Fernando," Wolff told Sky Sports. "He is a driver I respect a lot. He combines talent, speed and experience. It's all there."

However, the cost of buying out Alonso's contract and the Spaniard's turbulent relationship with Hamilton could yet prove to be stumbling blocks.

Alonso and Hamilton had one troubled season together at McLaren, leading to the Spaniard leaving the team after agreeing an early release from his contract.

Two-time champion Alonso is entering the final year of his contract, which may force Mercedes to look elsewhere.

Who will replace Rosberg at Mercedes?

With testing due to begin in February, the constructors' champions will have to move quickly to find a replacement.

Former Mercedes test driver Pascal Wehrlein, 22, remains the most realistic target to join British three-time champion Hamilton, who recently said he "doesn't care" who Mercedes pick.

Wolff added: "He [Alonso] is in a contract with McLaren-Honda at the moment and we just need to weigh all the other options up.

"Both drivers will have equal status and equal opportunity to the best of our abilities. We owe it to the fans. You can't have a pecking order."

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Analysis

BBC Sport chief F1 writer Andrew Benson:

Mercedes would think carefully before trying to tempt Fernando Alonso away from McLaren.

For one thing, buying him out of his McLaren contract would be expensive and the Spaniard had a troubled relationship with Hamilton when they were team-mates at McLaren in 2007.

Then McLaren team boss Ron Dennis reneged on a promise to give Alonso priority status and the two fell out, leading to Alonso leaving the team after just one year of a three-year contract.

The favourites for the seat alongside Hamilton remain Mercedes junior Pascal Wehrlein and Williams driver Valtteri Bottas, who has close links with Wolff.

Taking Bottas would also require Mercedes to do a deal with Williams, to whom the Finn is under contract until the end of 2017, but this may be easier than with McLaren as the team use Mercedes engines.

Ferrari's Sebastian Vettel has appeared to rule himself out of the equation.

The four-time champion is under contract until the end of next season and the German said at a Ferrari event at the weekend that "it should be clear" he was not an option.