Ymer the Elder has had a grueling season and now made his first match in eight weeks due to an elbow injury.
It also started well for the 123-ranked Swede who accounted for two serve breakthroughs at the start of the match and stormed up to the 3-0 lead.
But then came the problems.
A rusty Ymer served poorly and had problems with his forehand. Ymer was positioned to serve home the first set both at lead with 5-4 and 6-5, but missed both chances and Sugita, ranked 129th in the world, could win the first set in the tiebreak.
In others, the Japanese won directly in 23-year-old Ymer's servegame and could easily take home the set.
Mikael Ymer, who won a challenger tournament in France this weekend, sat on the stand and led with his brother. The 21-year-old, who is 75th in the rankings, is now the only Swedish jump in the singles tournament where he enters on Wednesday when Portuguese Joao Sosa waits in the first round.
For Sugita, Italian Stefano Travaglia awaits in the second round.