Albian Ajeti's move to Celtic has stalled after the player asked for more time to weigh up his options.
The West Ham forward was due to undergo a medical with the Scottish champions on Wednesday, but he stayed in Switzerland to allow for more time to consider the switch.
The Scottish champions agreed a season-long loan deal with West Ham for Ajeti on Monday. The deal includes an option to buy, for a fee of around £5m.
Celtic have been interested in Ajeti since last summer, before he made an £8m move to West Ham from Basel.
A number of Premier League clubs, including West Brom, are also interested in the Swiss international - and the player is now mulling over what's best for his career at this stage.
The 23-year-old struggled to establish himself at West Ham last season and was limited to nine substitute appearances in the Premier League.
The summer transfer window will run for 10 weeks from July 27 and close at 11pm on October 5. A domestic-only window for trades between the Premier League and EFL then runs from October 5 and closes on Friday October 16 at 5pm. Follow all the news and analysis on Sky Sports News and across Sky Sports' digital platforms.