Novak Djokovic returns the ball against Roberto Carballes Baena during the US Open first round on Monday. Photo: IC

Novak Djokovic has called on the Davis Cup to merge with the ATP Cup in the future and believes home ties should return in the early rounds of the tournament. 

The 119-year-old Davis Cup is making its first appearance in its new format in Madrid, where 18 countries are competing for the prestigious trophy in one venue and across a single week.

Under the previous system, a winning team would have to play four weekends across the year and top players were increasingly dropping out, deeming the demands too high in an already-congested tennis calendar.  But the changes have proven controversial, not least because the ATP, which runs the men's tour, is launching its own international tournament in Australia, less than six weeks after this year's Davis Cup ends. 

"Scheduling was always an issue for both the ATP Cup and Davis Cup," Djokovic said Wednesday, after helping Serbia beat Japan with a 6-1, 6-2 win over Yoshihito Nishioka.

"In my opinion the idea, if it could happen, was the merge between the two and I think it's still open for the future. 

"Looking long-term, I personally don't think that the two events can co-exist six weeks apart. It's just a little bit too congested. 

"The most ideal time of the year is after the US Open, probably at the end of September, that would be the best time to have this super cup, whatever, one cup, hopefully in the future." 

But holding either tournament after the US Open will prove difficult given that week already carries the Laver Cup, the competition promoted by Roger Federer's management company Team8, contested between Europe and a Rest of the World team.