[7] In the 2012–13 season he scored twice in 24 appearances as he helped Kaiserslautern to a third-place finish in the German second tier only to miss out on promotion due to defeat in the promotion/relegation play-off with Hoffenheim.
[3] On 16 April 2014, he missed his first final of his career in the semifinal of DFB-Pokal by facing as a substitute a 5–1 loss from the German champions Bayern Munich.
[20] Fortounis missed a penalty before making an assist in the 90th minute to secure a 2–1 victory over 10-man Dinamo Zagreb in the Champions League in November.
[25] He scored his first goal in European competition on 25 February with a penalty kick in a 2–1 home defeat to Anderlecht that eliminated Olympiacos from the 2015–16 Europa League at the round of 32 stage.
[12][26] On 20 March, Fortounis became the third player in Olympiacos' history to score 10 goals and make 10 assists in a season (after Predrag Đorđević in 2001–02, 2002–03 and 2003–04, and Chori Dominguez in 2014–15).
[12] On 14 October, he was the man of the match away to Panionios; after providing the assist for Pape Abou Cissé's early equaliser, he won and then converted the late penalty that gave his side a 4–3 win.
[35] In March 2018, Fortounis opened the scoring with a penalty in the home derby with Panathinaikos, played behind closed doors as punishment for misbehaviour by supporters; the match ended 1–1.
[38] After two goals and an assist in a 5–1 defeat of F91 Dudelange in the Europa League group stage in November 2018, Fortounis was named in the tournament's Team of the Week.
[39] On 13 December against AC Milan, he converted an 81st-minute penalty that gave Olympiacos the two-goal winning margin needed to qualify for the knockout rounds.
On 18 September 2020, in the 2020–21 Super League Greece opener game, the entry of Fortounis in the beginning of the second half, along with his first goal in the season, changed the image of the match and Olympiakos started the championship with a 3–0 home win against Asteras Tripoli.
On 27 June 2021, he twisted into an unsuspecting phase during the first test match against Wolfsberger AC, resulting in a cruciate ligament rupture in his left knee.
Two years ago he suffered the same injury to his right knee in another test match against Hamburger SV (early July) and was out of action for six months.
On 30 August 2024, Fortounis joined Saudi Pro League club Al-Khaleej on a two-year deal, receiving a salary of €6.4 million per year.
Fortounis' debut with the Greece came against Belgium in February 2012 as a suspension with the U-21 side allowed Fernando Santos to call-up the Kaiserslautern's prospect to the senior squad.
Showing plenty of maturity against the Belgians, Fortounis was also given test runs against Slovenia and Armenia in the final two Greece friendlies ahead of UEFA Euro 2012.
[1] In an injury free season Fortounis' high volume playmaking is clearly depicted in him excelling in or topping most league stat categories for attacking players including goals, assists, successful passes and crosses as well as mistakes.