3–2. At the end of the 2011–12 season, Frei won the Double, the League Championship title and the Swiss Cup with Basel. At the end of the Swiss Super League season 2012–13 Frei won the Championship title and was Swiss Cup runner up with Basel. In the 2012–13 UEFA Europa League Basel advanced as far as the semi-finals, there being matched against the reigning UEFA Champions League holders Chelsea, but they were knocked out, losing both home and away tie, beaten 2–5 on aggregate. At the end of the 2013–14 Super League season Frei won his fourth 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. During the 2013–14 Champions League season Basel reached the group stage and finished the group in third position. Thus they qualified for Europa League knockout phase and here they advanced as far as the quarter-finals. In their season 2013–14 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). Frei totaled 66 appearances, 34 League, 6 Cup, 6 Champions League and 10 Europa League as well all 10 in the test games. The season 2014–15 was a very successful one for Basel and for Frei. The championship was won for the sixth time in a row that season and in the 2014–15 Swiss Cup they reached the final. But for the third season in a row, they finished as runners-up, losing 0–3 to FC Sion in the final. Basel entered the Champions League in the group stage and reached the knockout phase as on 9 December 2014 they managed a 1–1 draw at Anfield against Liverpool. Frei scored the goal for FC Basel against Liverpool to help Basel to the next round of the UEFA Champions League. But then Basel then lost to FC Porto in the Round of 16. Basel played a total of 65 matches (36 Swiss League fixtures, 6 Swiss Cup, 8 Champions League and 15 test matches). Under trainer Paulo Sousa Frei totaled 56 appearances, 31 in the Super League, 5 Cup, 8 Champions League, as well 12 in test games. He scored a total of 4 goals in these matches. Mainz 05 On 23 June 2015, Frei joined German Bundesliga club 1. FSV Mainz 05. Return to Basel On 23