Tottenham defender Jan Vertonghen has told Sky Sports that Mauricio Pochettino's decision to keep the squad in London for pre-season was a good one.
The Belgian international, 28, has left White Hart Lane to join up with his national team-mates ahead of games against Andorra and Israel, with a place at Euro 2016 in France on the line.
Spurs will be hoping and praying that Vertonghen returns from international duty unscathed, given that the centre back has found his best form again alongside summer signing and Belgian team-mate Toby Alderweireld.
Their partnership in defence has been a major factor in Spurs' promising start to the season, but many believe that the biggest thing for Pochettino's men has been their fitness.
It was seen last season with a number of late victories, but Spurs' fitness under Pochettino has been superb, with Tottenham rallying in the dying embers of games whilst their opponents wear themselves out.
Now, defender Vertonghen has admitted to Sky Sports that a gruelling pre-season, which focused on staying in London for the majority of the summer, save for trips to the United States and Germany, has been huge in Tottenham's start to the season.
"Yeah, very hard!" said Vertonghen when asked whether Spurs had been training hard. "I think everyone knows we went through a tough pre-season, and a good one. I think it was very important that we stayed in London. I think it was a very good decision by our manager."
"We show that now, every time, if it's in Europe, Capital One Cup or Premier League, we keep fighting until the end, and we see something different in our opponents," he added.