Transfer Rater: Diego Costa to Besiktas, Thomas Muller to Arsenal

Things change in the blink of an eye in football. The Football Whispers Index takes the latest transfer rumours and gives them a score out of five; the higher the score, the more realistic and reliable the whisper.

Here are today's top five emerging whispers. And keep an eye on Transfer Talk for all the latest gossip.

Atakan Akkaynak to Chelsea

Chelsea are battling it out with Roma and Barcelona for the signature of Bayer Leverkusen midfielder Akkaynak. The 18-year-old is yet to make his debut for the first team but is considered to be one of the best talents in his age group, and teams want to snap up the defensive midfielder before he bursts on to the scene. According to Goal, manager Antonio Conte has put Akkaynak at the top of Chelsea's list of summer targets.

Bacary Sagna to Arsenal

After selling Alex Oxlade-Chamberlain to Liverpool and loaning Carl Jenkinson to Birmingham, Arsenal aren't blessed with an abundance of right-back options and the transfer window is closed for another four months. However, the Gunners are able to bring in a player if they're a free agent, and reports in the Daily Express claim the club are looking to do just that. Bacary Sagna, unattached since leaving Manchester City in the summer, is in the middle of a tug-of-war between Arsenal and Torino, who lost starting right-back Davide Zappacosta to Chelsea on deadline day.

Andre Gomes to Tottenham

Tottenham are planning a fresh approach for Barcelona midfielder Gomes in January. A deal was almost struck on the final day of the summer window but the Catalan giants pulled the plug after being unable to bring in a replacement. The Daily Star claims Mauricio Pochettino's side are in pole position should the Portuguese playmaker be allowed to leave the Camp Nou.

Diego Costa to Besiktas

According to reports in OKDiario, Costa is a top target for Besiktas and the Turkish side are looking to press on with a move for the Chelsea striker before the transfer window in Turkey closes. Costa wanted to return to Atletico Madrid but the Spanish club can't register players until January, meaning Costa is in limbo after being told he has no future at Stamford Bridge.

Thomas Muller to Arsenal

Premier League rivals Arsenal and Chelsea are going to continue monitoring Muller's situation at Bayern Munich ahead of a potential January move. According to SportBild, both clubs made enquiries for the player before the transfer window shut but were knocked back. However, the Daily Mirror suggest the two clubs will return for the player if he continues to be overlooked by Carlo Ancelotti.