Young Boys made it 15 wins from 21 games with a 2-1 victory at St. Gallen.
Alberto Regazzoni was the star of the show for the visitors, netting in the 37th and 65th minutes to send Young Boys four points clear of Basle at the top of the table.
Moreno Merenda grabbed a consolation for St. Gallen.
Third-placed Lucerne were 2-1 winners against struggling Bellinzona.
Ildefons Lima gave the visitors a shock lead two minutes before half-time, but Davide Chiumiento netted from the penalty spot before the break and the striker then grabbed the winner ten minutes from time.
Draw for Xamax
Fourth-placed Neuchatel Xamax stayed ahead of Sion on goal difference after a 1-1 draw between the sides.
Abdou Rahman Dampha cancelled out Emile Mpenza's early opener for Sion, who had Serey Geoffroy sent off 13 minutes from time.