Chelsea are leading the race for highly-rated Portugal youngster Ruben Neves and will demand a decision on a move to Stamford Bridge in the first week of November.
The 19-year-old has made a fine start to the season with Porto and that has tempted the Blues to force their way to the top of the pecking order, with Liverpool, Valencia and Juventus also interested.
All three teams have had the player watched, but it is understood the west London club have the best chance of capturing the Porto midfielder, who made his breakthrough in 2014.
Chelsea are ready to offer £24 million up front and a player, plus add-ons, however, where the Portuguese giants will accept such an offer remains to be seen.
Liverpool, though, will be keen to lure the youngster to Anfield, under the guidance of Jurgen Klopp, who has a fine record of developing young players.
But the Blues want to bring Neves in by January, while Juventus want a midfield reinforcement following the departures of Andrea Pirlo, Arturo Vidal and Paul Pogba over the last 18 months.