At the end of the 2013–14 season, Sommer won the league championship with Basel. They also reached the final of the 2013–14 Swiss Cup, but were beaten 2–0 by Zürich after extra time. In the 2013–14 Champions League, Basel finished the group stage in third position to qualify for Europa League knockout phase, where they advanced as far as the quarter-finals. In their 2013–14 season, Basel played a total of 68 matches: 36 Swiss League fixtures, 6 Swiss Cup, 6 Champions League and 10 Europa League and 10 test matches. Sommer totaled 58 appearances: 35 League, 2 Cup, 10 Champions League and 6 Europa League, as well 5 in the test games.
