The 2017–18 season was Sport Lisboa e Benfica's 114th season in existence and the club's 84th consecutive season in the top flight of Portuguese football. It started on 5 August 2017 with Benfica's victory in the Supertaça Cândido de Oliveira and concluded on 13 May 2018.
Benfica played in the Primeira Liga as four-time defending champions for the first time in their history and finished second. Benfica also entered the Taça de Portugal as title holders but were eliminated in the fifth round. Moreover, they were eliminated in the third round of the Taça da Liga.
Internationally, Benfica competed in the UEFA Champions League for the eight time in a row but failed to gain a single point in the group stage for their first time, finishing with a negative goal difference of 13, which became the worst campaign of a Portuguese team in that competition.
Season overview
On 29 June 2017, club president Luís Filipe Vieira gave the motto for the coming season, "Rumo ao Penta", and promised a renewed ambition to conquer an unprecedented fifth-straight Primeira Liga title for Benfica. The following day, manager Rui Vitória explained his approach to the new season: "We know that there's a goal previously assumed by the President and the best way to achieve it is to go on together, like it was the first time. It is fundamental to have the first time ambition. Humble and focused so that it can happen." Despite the ambition, on 31 July, Vieira said "one can mortgage a title or another but not the future [of the club]", referring to a strategy of managing the club's debt through the sale of players.
Transfers
Haris Seferovic, Filip Krovinović, Martin Chrien and Bruno Varela transferred to Benfica. Diogo Gonçalves and Rúben Dias were promoted from Benfica B and João Carvalho integrated the team after a loan spell at Vitória de Setúbal.
Benfica lost three players from the starting 11 before the season started: on 1 June, Ederson signed with Manchester City for €40 million; on 14 June, Victor Lindelöf left to Manchester United for €35 million; and on 14 July, Nélson Semedo moved to Barcelona for €30.5 million. On 31 July, referring to the club's sales, Vieira said, "Until we do not have control over the debt, we will not stop selling."
Later in August, Benfica loaned out André Carrillo to Watford and André Horta to Braga, while Mile Svilar joined from Anderlecht. On transfer deadline day, Benfica announced the signings of Douglas and Gabriel Barbosa, both on a one-year loan spell from their respective clubs. The same day, Kostas Mitroglou, Benfica's top goalscorer in the previous season, was transferred to Olympique de Marseille for €15 million.
During the mid-season transfer window, Lisandro López signed with Inter Milan on a half-year loan deal with an option to make the switch permanent. On 25 January, Filipe Augusto was loaned out to Alanyaspor for one-and-a-half years and Barbosa's contract was terminated.
Pre-season
The pre-season started on 30 June 2017 with the usual medical exams and physical tests at Caixa Futebol Campus and at Hospital da Luz. Until 12 July, the work schedule took place on the club's training ground. As for the team's commitments, the program included the Uhrencup in Switzerland, a five-day stay in Algarve with two matches, and a stage at St George's Park in England, from 23 to 28 July, before the Emirates Cup. Benfica finished third in the Swiss tournament after a 5–1 defeat to Young Boys. The team redeemed itself with a victory in the Algarve Football Cup thanks to a brace by newly signed Seferovic. On 26 July, Benfica played a behind-closed-doors friendly against Swindon Town at Futebol Campus, where Seferovic and Andrija Živković scored for Benfica in a 2–1 win. Once again, Benfica stood powerless in the Emirates Cup. By losing both matches, the team repeated its fourth-place finish achieved in 2014. Due to Chapecoense's cancellation, Benfica did not host the Eusébio Cup in the pre-season for the first time since its first edition in 2008.
As with the previous season, Benfica kept struggling with player injuries. On 17 June, Álex Grimaldo did not take part in Spain's squad for the UEFA European Under-21 Championship due to a "little injury" resulting in him missing the start of Benfica's pre-season. Nine days after signing with Benfica, Krovinović underwent surgery on 23 June to correct a left inguinal hernia. He was one of three players absent from the squad who travelled to Switzerland, along with Luisão (right knee injury) and Eduardo Salvio (right tibiotarsal sprain). André Almeida suffered a contusion on his right thigh, which prevented him from travelling to Algarve.