Roberto Soldado and Erik Lamela were among the goalscorers as Tottenham comfortably saw off Celtic at the Olympic Stadium in Finland's capital.
Spurs raced into a 2-0 lead thanks to efforts from Harry Kane and Soldado.
Jamie Lindsay pulled a goal back for Celtic in the 43rd minute, but just a minute later Lewis Holtby restored the two-goal cushion and Tottenham kept the momentum going after the break.
Lamela - who, like Soldado, is looking to bounce back after a disappointing first season with the London club - made it 4-1 just before the hour mark.
A Christian Eriksen free-kick and Emmanuel Adebayor penalty wrapped up the rout in the last 10 minutes, while Celtic's misery was compounded by a red card for Efe Ambrose - his second this week, having been dismissed in Wednesday's Champions League qualifier against Legia Warsaw.
Arsenal striker Yaya Sanogo scored four goals as Benfica were swept aside 5-1 in the Emirates Cup.
The France Under-21 striker did not manage to find the net in any of his 14 appearances last season, having joined from Auxerre on a free transfer.
Sanogo produced a clinical display as he bagged a first-half hat-trick while Costa Rica forward Joel Campbell, back from a loan spell at Olympiacos, also impressed, scoring the other Arsenal goal.
Summer signing Alexis Sanchez was introduced from the bench in the 74th minute for his Arsenal debut.
In the earlier Emirates Cup kick-off, Monaco twice came from behind to draw 2-2 against Valencia.
Colombia striker Falcao, who missed the World Cup because of a serious knee injury, made an appearance off the bench for Monaco in the closing stages, his first since January.
Newcastle, playing in the Schalke Cup tournament at the Veltins Arena, conceded three goals in 18 first-half minutes on the way to a 3-1 loss to Spanish side Malaga.
Sergi Darder opened the scoring in the 25th minute with a long-range strike that went in off the woodwork.
Samu Castillejo volleyed in at the far post in the 32nd minute and the same man then netted a deflected effort towards the end of the half before Gabriel Obertan fired in a consolation on the hour.
Competing in the same tournament in Gelsenkirchen, West Ham drew 0-0 with hosts Schalke before triumphing 7-6 on penalties.
The Hammers had survived a few scares during the 90 minutes, with their German opponents hitting the woodwork twice.
Aston Villa slumped to a 4-1 defeat away against Dutch side Groningen after conceding two goals in the opening eight minutes.
Both of those were scored by Tjaronn Chery, and Jarchinio Antonia then made it 3-0 on the half-hour at the Euroborg. Charles N'Zogbia responded with a free-kick with around 15 minutes to go, but Groningen were not done and Dino Islamovic added their fourth in the last few seconds.
Summer signing Bafetimbi Gomis was on the scoresheet for Swansea as they beat Reading 3-1 at the Madejski Stadium.
The France striker provided a cool finish to seal the victory in the second half.
Wayne Routledge had earlier - after Wilfried Bony crashed a penalty against the crossbar - scored twice in three minutes to put the Swans in charge, with the hosts replying through a Nick Blackman wonderstrike.
Crystal Palace suffered a 3-2 defeat at Championship newcomers Brentford.
A flurry of goals early in the second half saw Jonathan Douglas and Andre Gray put the home team 2-0 up and Palace then draw level through Glenn Murray and Marouane Chamakh.
Moses Odubajo went on to net the winner.
A Stoke XI drew 0-0 at Burton and West Brom went down 1-0 at Nottingham Forest courtesy of a Matty Fryatt goal.
Charlie Austin and Junior Hoilett scored a brace apiece in QPR's 4-0 win at Shamrock Rovers, while summer recruit Marvin Sordell's effort steered Burnley to a 1-0 triumph at Blackpool.
Sunderland were held to a goalless draw by Vitoria Setubal in the last of their three friendlies in Portugal.
The draw in Albufeira comes after Gus Poyet's men had beaten Recreativo Huelva 1-0 before losing to CD Nacional by the same scoreline.
Leicester drew 1-1 at Preston, with Liam Moore's goal cancelled out by a Tom Clarke header.
Chris Martin scored twice as Derby concluded their pre-season campaign with a 2-0 win over Rangers at the iPro Stadium.
Leeds claimed an encouraging 2-0 victory over Dundee United at Elland Road.
Steve Morison and substitute Dominic Poleon scored the goals for Dave Hockaday's side.