Aarau kept in touch with the leaders from Liechtenstein in the Challenge League after losing the top match in Vaduz.
Coach Brunello Iacopetta's team won 1:0 at home against bottom side Bellinzona on Saturday.
Elias Filet's goal in the 10th minute was the only one of the game. Vaduz had opened the scoring the day before with a 3-1 win against Wil, their tenth victory in a row. The two dominant teams in the league are now separated by four points.
The second game on Saturday also ended with a 1-0 home win. Filipe De Carvalho secured FC Rapperswil-Jona the three points against fourth-placed Stade Lausanne-Ouchy with a goal after half an hour.