Mauricio Pochettino admits Tottenham have run into a "bad period" after they suffered a surprise defeat to Gent in the Europa League last 32.
Spurs' disappointing night in Belgium was also compounded by Harry Kane sustaining a knock to his knee.
Kane later suggested the injury was not serious but the striker is still unlikely to be risked against Fulham in the FA Cup on Sunday.
Jeremy Perbet's second-half winner secured Gent a 1-0 victory at the Ghelamco Arena and leaves Tottenham with work to do in next week's second leg at Wembley if they want to progress.