Various reports have suggested that the two clubs are close on an agreement for Gallagher as Mauricio Pochettino could lose a key component of his team during a disappointing start to his reign at Stamford Bridge.
MORE TO FOLLOW
We’ll be bringing you the very latest updates, pictures and video on this breaking news story.
For the latest news and breaking news visit: express.co.uk/sport/football. Stay up to date with all the big headlines, pictures, analysis, opinion and video on the stories that matter to you.
Follow us on Twitter @dexpress_sport – the official Daily Express & Express.co.uk Twitter account – providing real news in real time.
We’re also on Facebook @dailyexpresssport – offering your must-see news, features, videos and pictures throughout the day to like, comment and share from the Daily Express, Sunday Express and Express.co.uk.