Bundesliga clubs Bayern Munich, Borussia Dortmund and Wolfsburg all began their preseason friendlies but experienced mixed results in Saturday's action.
U.S. international Julian Green scored and forced an own goal but Arjen Robben picked up a thigh injury as Bayern Munich beat fifth-tier Lippstadt 4-3 in in Carlo Ancelotti's first game in charge.
The Italian named a strong side that included Franck Ribery, Javi Martinez, Xabi Alonso and Philipp Lahm for the occasion.
Green tapped in a rebound from close range in the ninth minute to open the scoring before Robben and Ribery within 33 minutes staked the Bundesliga champions into a 3-0 lead.
- FC Bayern München (@FCBayern) July 16, 2016
But Robben was replaced by Mario Crnicki after pulling up injured during the first half.
"He felt something in his muscle," Ancelotti said after the game. "The doc will examine it. I hope it's nothing serious."
Early in the second half, Green forced an own goal from Lippstadt to make the lead even more convincing before Ancellotti put on the reserves and the Oberliga Westfalen side fought back.
Goals from Marcel Rump, Stefan Parensen and Paolo Maiella in the final 38 minutes made for a nervy ending.
Borussia Dortmund, however, lost in their fourth preseason game of the summer, falling 1-0 at 1860 Munich.
Manager Thomas Tuchel named a competitive XI, featuring Matthias Ginter, Marcel Schmelzer, Sokratis Papastathopolous, Shinji Kagawa and summer signings Sebastian Rode and Ousmane Dembele against the second-tier outfit.
Levent Aycicek put 1860 ahead in the first half with a fine finish, latching onto a loose ball in the Dortmund half, running 20 yards towards goal and firing beyond reserve goalkeeper Hendrik Bonmann.
Dortmund created several chances to equalise in the second half but Aycicek's strike proved to be the only goal of the game.
In Scotland, Wolfsburg lost 2-1 to Celtic in a game that also saw the debut of safe standing at Celtic Park.
A total of 2,600 seats were successfully converted and supporters enjoyed a solid win, just days after Brendan Rodgers' side lost 1-0 to Gibraltar's Lincoln Red Imps in Champions League qualifying.
Wolfsburg took an early lead after 11 minutes, with Paul Seguin's shot deflecting off a defender and wrong-footing goalkeeper Craig Gordon.
Callum McGregor levelled on 24 minutes and substitute Ryan Christie completed the comeback in the 62nd minute.
Schalke also suffered a defeat, falling 4-2 to Luzern in Switzerland.
Markus Neumayr penalty had the hosts up inside two minutes, before Marco Schneuwly scored twice after half-time. Schalke got goals from Klaas Jan Huntelaar and Matija Nastasic, but Luzern's Joao De Oliveira made it 4-2 in the 89th minute to end the comeback.
Werder Bremen had no such troubles, beating Neuruppin 8-0 with a Johannes Eggestein hat trick, and then drawing 1-1 with Luebeck later in the day.
Antonio Conte's first game in charge of Chelsea ended in a 2-0 defeat against Rapid Vienna.
A strong side captained by John Terry and including Branislav Ivanovic, Nemanja Matic, Willian, Ruben Loftus-Cheek and Diego Costa fell behind to Brazilian teenager Joelinton's eighth-minute goal.
Tomi Correa added a second with eight minutes remaining while, for the Blues, Costa squandered a good chance and academy graduate Ola Aina hit a post.
Jose Mourinho made a winning start as Manchester United manager as his side secured a deserved and comfortable 2-0 victory in their opening match at Wigan Athletic.
Substitute Will Keane scored the first goal, tapping in after a blunder by 41-year-old goalkeeper Jussi Jaaskelainen in the 49th minute. Andreas Pereira, another man who had come on for the second half, then rifled in another goal 10 minutes later.
Brendon Galloway scored in the second half as Everton opened the Ronald Koeman era with a 1-0 win over Czech side Jablonec in Austria.
Stoke City's opening game ended in a 3-0 defeat against Championship new boys Burton Albion. Chris O'Grady scored twice in the second half and Lucas Akins completed the scoring at the Pirelli Stadium.
However, Stoke boss Mark Hughes will have been heartened by the return of goalkeeper Jack Butland and defenders Glen Johnson and Marc Wilson after long-term injury lay-offs.
Saido Berahino shrugged off the latest speculation about his future with two goals as West Brom beat Kidderminster 2-1.
The striker, who is once again being linked with a move away from The Hawthorns, scored in each half for the Baggies, who also gave a run-out to new signing Matt Phillips.
Rickie Lambert and youngster Andre Wright earned another Albion XI a 2-1 win at Stafford Rangers.
Stewart Downing and Alex Pattison scored in Middlesbrough's 2-0 win over Doncaster, while Greg Olley and Greg Luer netted either side of half-time to help Hull City beat North Ferriby United 2-0.
In the U.S., Swansea City suffered a 2-0 defeat to Richmond Kickers. A Jordi Amat goal put the hosts ahead early, and after a lengthy thunderstorm delay, an Anthony Grant goal sealed the win.
Crystal Palace had better luck in America, easing to a 2-0 win at FC Cincinnati, Jordon Mutch and Wilfried Zaha on target.
Suso scored twice in the first half to give AC Milan a 2-1 win over Bordeax, who pulled a goal back through Malcom after the break.
The Brazilian team had two more chances to find an equaliser but Milan held on to win Vincenzo Montella's first game in charge.
Bologna thrashed amateur side Virtus Acquaviva 9-0 thanks to four goals from Simone Verdi -- just arrived from Milan -- two from Sergio Floccari, and one each from Ibrahima Mbaye, Franco Brienza and Saphir Taider.
Chievo suffered a 3-0 defeat to Belgian powers Standard Liege, Ivan Santini, Dino Arslanagic and Mathieu Dossevi finding the net.
Udinese let a two-goal lead slip and settled for a 2-2 draw with Krasnodar. After Cyril Thereau and Emmanuel Agyemang-Badu put Udinese up, the Russian club struck back through Odil Akhmedov and Fedor Smolov.
Kevin Gameiro scored in the third minute to help Sevilla to a 3-1 win over Argentine giants River Plate.
Yevhen Konoplyanka added a second goal on the hour mark, and Steven N'Zonzi put in a third six minutes later.
Alfonso Pedraza scored two minutes from time to give Villarreal a late 1-0 win over third-tier club L'Hospitalet.
Youssef En-Nesyri scored twice in the first half and Charles and Michael Santos both added goals as Malaga handled Algeciras 4-0.
Granada beat fourth-tier Mar Menor 6-0 with a late brace from David Barral, while Deportivo La Coruna also cruised, beating Negreira 10-1 after hat tricks from Lucas Perez and Oriol Riera.
Jonathas scored twice as Real Sociedad ran out 5-0 winners over Tolosa, with Esteban Granero, Juanmi and Ruben Pardo also scoring.
Celta Vigo let an early lead slip after Mendez's opener in a 2-1 defeat to Lugo, while newly promoted Alaves were held in a goalless draw by Real Union.
Nice wore black armbands in their first game since their attack in their home city this week, a 1-1 draw in Switzerland with Servette.
Gabriel Boschilia's first-half goal was all Monaco needed to beat Basel, though Saint-Etienne fell 4-1 to Lausanne.
Lille could not find a breakthrough in a 0-0 draw with Belgium's Oostende while Metz beat Seraing United 3-1, and Rennes defeated Algeria's USM Alger 1-0.
Ligue 2 sides had great success against top-flight opponents as Bob Bradley's Le Havre controlled Caen 3-0, while AC Ajaccio whipped Bastia 4-0, Angers lost to Niort 1-0, Sochaux defeated Dijon 2-0, Guingamp fell 2-0 at Brest and Nancy were held to a 1-1 draw at Reims.
Lyon's scheduled match against Fenerbahce was cancelled after the attempted coup in Turkey on Friday night.