The Lions series against the world champion Springboks remains pencilled in for July next year but South African Rugby have confirmed there is a "slight chance" it could be moved to align with a new global calendar.

The Lions tour has a planned 3 July, 2021 start, with the three Tests on consecutive weekends from 24 July onwards, but a mooted change to the sport's global calendar could see a switch.

"The tour is going on and the time is still fixed on where it is, but there might be a date change," SA Rugby CEO Jurie Roux said in a press briefing on Monday.

"There is a slight chance that, to align with a new global calendar, it might move to either a September/October or October/November window and that is only because if that is the only hurdle of getting the global calendar across the line, we wouldn't want to be the hindrance to that."

Roux said a decision on the suggested global calendar shift, which would do away with mid-year internationals, could come as soon as 1 July, which would provide certainty on when the Lions tour will take place.

"Second only to the World Cup, it is the biggest thing on the calendar," Roux added. "The commercial model we have put up as a joint venture between us and the Lions is actually pretty 'out there'.

"We have thrown away the textbook on it. It is a completely different model. It is a sharing of revenue, logos and IP (intellectual property) and commercial value, and something that in a post-Covid world will help us operate as a going concern."

Negotiations to align the club and international calendar to ease fixture congestion have been accelerated by the impact of the Covid-19 pandemic on the sport.

Among the ideas under discussion is a shift of the Six Nations Championship, possibly to a month or two later than its current February/March slot, and for Europe to adopt more of a summer club rugby season.