Britain's Cameron Norrie and Jack Draper were both knocked out in the first round of the Japan Open.
Despite leading by a set and a break, Draper lost 4-6 7-6 (7-4) 7-6 (7-1) to Australia's Alex de Minaur.
British number two Dan Evans plays Austrian Filip Misolic in the first round of the Stockholm Open on Tuesday.
From 4-2 up in the first set, Scot Norrie lost seven successive games en route to an 11th defeat in 14 matches.
World number 10 Fritz will meet Japanese wildcard Shintaro Mochizuki or Argentina's Tomas Martin Etcheverry in the second round.