The 23-time grand slam winner planning to resume career fourth months on from expected due date.
The previous record was also in Montreal with 213,760 spectators.
Nadal will be confirmed as the world No1 when the rankings are recalibrated at the end of this week.
The 36-year-old suffered back problem in Rogers Cup final loss to Alexander Zverev.
Swiss star could become the oldest world number one ever if he wins the latest Masters 1000 event.
Both Federer and Nadal can become the new world number one depending on their results.
Federer and Nadal will battle for top spot in the men's singles rankings at this week's Cincinnati Masters.
Federer will meet Zverev in a final for the second time since June.
Nadal exited the Rogers Cup after his third round loss to the Canadian.
Nadal can take over the top ranking from Murray by making the semi-finals at the Rogers Cup.
The 19-time grand slam champion wins opening match at Rogers Cup by beating Peter Polansky.
Three-time major champ now a big doubt for the US Open due to ongoing hip injury.
The Spaniard jokes "leave something for the young ones" as Federer prepares to return.
Federer begins his hard-court campaign in Montreal ahead of the US Open.
Two-year rankings would allow more players to take breaks and rest up.
Nadal can become world No1 if he makes the semi-finals at the Rogers Cup this week.
Nadal is on course to regain his world number one ranking at the Rogers Cup.
The legendary pair continue to roll back the years and are the top two seeds for the Rogers Cup.
The Swiss number two is "extremely disappointed" about not being able to defend title at Flushing Meadows.
Nadal could become the new world number one with a win in the Rogers Cup.
Federer will be looking for his sixth title of the year ahead of the US Open.
Federer won his 19th men's singles Grand Slam title at Wimbledon this year.
Thiem is one of many young players who are expected to be the new generation.
Injuries and poor form have disrupted Murray's year so far.
Nadal is just 285 points behind world number one Andy Murray.
Nadal has won four titles in the calendar year so far, including a 10th French Open title.
Former world number one has never previously missed a Grand Slam, but will not play at next month's US Open.
Federer has won 19 men's singles Grand Slam titles - four more than Nadal in second.
The tennis star is fighting a multi-million dollar lawsuit after a car crash in early June.
Federer is considered to be one the greatest to play the game and a role model for emerging players.