A new-look Tottenham slipped to a 1-0 defeat at Pacos de Ferreira of Portugal in their Europa Conference League play-off first leg on Thursday.
Coach Nuno Espirito Santo made 11 changes to the team that defeated champions Manchester City in their Premier League opener at the weekend.
Not surprisingly, it was a disjointed performance by the Londoners who were again without England star Harry Kane.
Three of Tottenham's summer signings started the game -- goalkeeper Pierluigi Gollini, defender Cristian Romero and winger Bryan Gil.
Teenagers Nile John and Dane Scarlett were handed chances to shine while identical twins Michael and Matthew Craig were on the bench.
Lucas Silva struck the only goal on the stroke of half-time for the home side.
The 23-year-old Brazilian striker, signed from Flamengo last year, nipped in behind the Tottenham defence to slot home the chance.
"The decision was to try to give minutes to players, to get minutes on their legs and increase the levels of fitness," Nuno told the BBC.
"Of course things take some time."
In Turkey, former Tottenham boss Jose Mourinho enjoyed a winning start with Roma as the Italian side edged out Trabzonspor 2-1.
Mourinho fielded three new signings in his team and it was one of those, Eldor Shomurodov who grabbed the winner.
With 10 minutes left, the Uzbek striker, signed from Genoa in the summer, was fastest to react when a header from Gianluca Mancini came back off the post.
Lorenzo Pellegrini had given Roma a 55th-minute lead when Henrikh Mkhitaryan, another new arrival, played in the decisive pass.
The Turks were level 10 minutes later when substitute Andreas Cornelius headed in just moments after replacing Gervinho.
"This is not a Conference League level opponent, it felt more like a Champions League play-off," Mourinho told Sky Sport Italia.
"They have a lot of experienced players. There was pressure and if anyone thought this would be easy, they were mistaken."
Elsewhere, Colombian striker Luis Sinisterra scored a hat-trick as 1970 European Cup winners Feyenoord trounced Elfsborg of Sweden 5-0.
In a tie featuring the most westerly club in a European top flight, Santa Clara of Portugal, who are based in the Azores, defeated Partizan Belgrade 2-1.
In the Europa League play-offs, Greek champions Olympiakos closed in on the group stage with a 3-0 home win over Slovan Bratislava.
Mady Camara, Pape Abou Cisse and an own goal from Vasil Bozhikov secured the victory.
Galatasaray, defeated in Champions League qualifying by PSV Eindhoven, drew 1-1 at Randers who were only sixth in the Danish league last season.
Antwerp endured a tough start to their campaign, losing 4-2 at Cypriot champions Omonia Nicosia.
Scottish champions Rangers edged out Alashkert of Armenia 1-0 at Ibrox having played the entire second half with 10 men following a red card for John Lundstram.