Lucien Favre admitted his young players struggled to break down Club Brugge after Christian Pulisic's late goal earned Borussia Dortmund a 1-0 win in their Champions League opener.
Favre handed a place in his starting line-up to 18-year-old playmaker Jadon Sancho, but it was second-half substitute Pulisic, on his 20th birthday, who turned the game with his strike in the 85th minute.
The result ensured Dortmund remain unbeaten in five games in all competitions this season, but Favre pulled no punches when discussing the challenges his players faced during a first half in which they were second best.
"It was difficult," he told reporters. "They are Belgian champions and they worked hard.
"In the end, they were tired, but it was difficult - it was very, very hard for us. We did not move enough in the first half, which is why we struggled to create chances.
"We are satisfied that we have won our first away game. But we have had trouble and we have much to do.
"It is a very good thing that we won, but we should not exaggerate expectations.
"We have many young players, it takes time to play well."
The late goal denied Brugge a share of the points in a tough Group A that includes Atletico Madrid and Monaco.
Midfielder Arnaut Groeneveld remained defiant, however, saying: "The result is disappointing.
"In the first half we played our own game, we had more ball possession. But we started with confidence in the second half as well and that makes the final result a bit harsh.
"I think everyone can see now that if we play our own game we can do pretty well. I think we will just need to continue like this and the points will follow."
|Titans CB Logan Ryan out for season with broken leg|
|Suns send Trevor Ariza to Wizards for Kelly Oubre, Austin Rivers|
|Mourinho charge for ´improper´ language dismissed|
|Are the Knicks for sale? Depends on the offer, says Dolan|
|Klopp´s Liverpool are vulnerable – Neuer|
|Warrington: Frampton not an elite fighter|
|I want to finish the job off - Yates confirms Giro d´Italia focus in 2019|
|Atletico confirm Filipe Luis hamstring injury|
|Best backs Schmidt to lead Lions in 2021|
|Barcelona´s Vermaelen out for a month with calf injury|
|India lose Shaw for Australia tour as defeat looms in Perth|
|We didn´t have much luck - Nedved dismayed by Atletico tie|
|Manchester City must control Schalke, Begiristain warns|
|Ibrahimovic hints at LA Galaxy stay|
|Latham fills his boots in Wellington with record-breaking knock|
|I´m not thinking ´thank God it´s Bayern´ – Klopp|
|Luis Garcia and Steve McManaman confident of Liverpool progress|
|Arsenal face BATE as Chelsea get Malmo in Europa League|
|Europa League last 32: Draw in full|
|Irwin urges Mourinho turnaround before PSG Champions League clash|
|Rush backs German Klopp to see off Bayern|
|Hope shines as West Indies blitz Bangladesh in Sylhet|
|United and PSG set for Champions League showdown|
|Ajax star De Ligt delighted to join Golden Boy alumni|
|Champions League last 16: Draw in full|
|Lyon strikes to put Australia on course for victory in Perth|
|Mourinho´s players below Manchester United standards, says Giggs|
|We´ve got to find a way to get better in a hurry - McVay challenges spluttering Rams|
|Van Dijk hails ´game-changer´ Shaqiri for downing Man United|
|LeBron praises magical Wall as Lakers fall flat on the road|
|Champions League last 16: Who could get who in Monday´s draw?|
|Pochettino urges fans to ´kill´ racism ahead of EFL Cup derby|
|Ajax star De Ligt wins Golden Boy award|
|Foles fuels Eagles´ upset win over Rams|
|Latham carries bat as New Zealand leave Sri Lanka reeling|
|Keep your cool, Virat – Paine and Kohli in another confrontation|
|Depleted Nuggets complete season sweep of Raptors|
|Fabinho was ´outstanding´, says Klopp|
|Patriots QB Brady on loss to Steelers: We aren´t playing well enough to win|
|Elliott says Cowboys´ shut-out loss to Colts was embarrassing|
|De Bruyne not worried about Liverpool title challenge|
|Sixers star Simmons makes history with triple-double|
|WATCH: Nowitzki receives standing ovation in first home game of season|
|Seattle´s playoff spot on hold after Seahawks suffer OT loss to 49ers|
|Cheika survives as Wallabies coach, Johnson appointed|
|Vikings remain in NFC playoff picture|
|Steelers stay ahead as Patriots lose AFC´s second seed|
|Lionel Messi is the best, says Amor|
|I´m still tired just looking at Robertson – Mourinho in awe of Liverpool intensity|
|Casillas takes swipe at Mourinho after United lose to Liverpool|
|Valverde relieved as Messi brilliance prevents another Levante nightmare|
|WATCH: Leno proposes to girlfriend after Bears clinch division title|
|Messi and Suarez the world´s best strike partnership, says Pique|
|Klopp: I cannot keep every Liverpool player happy|
|Messi and Suarez outscoring Real Madrid and Atletico in LaLiga|
|Levante 0 Barcelona 5: Marvellous Messi banishes ghosts of last season|
|Colts rout Cowboys to keep playoff hopes alive|
|Bears shake off Packers to win NFC North and return to playoffs|
|Mourinho explains Pogba omission and defends Lukaku´s Liverpool showing|
|Liverpool´s display against Manchester United one of the best, claims Klopp|
|Look away Jose! Damning stats expose Manchester United´s limp Liverpool loss|
|Time´s up, Mourinho: Manchester United can dither no longer|
|Manchester United´s players are not dishonest – Mourinho|
|Manchester United´s lack of ambition under Mourinho is scary – Keane|
|Mourinho: All Manchester United can achieve is fourth|
|Quagliarella should be protected by UNESCO, jokes Sampdoria coach|
|Manchester United surpass last season´s goals-against tally in first 17 games|
|Hasenhuttl revels in ´unbelievable´ victory over Arsenal|
|Liverpool 3 Manchester United 1: Shaqiri´s late show bails out Alisson as Reds return to the top|
|Edinburgh in control in Champions Cup, Racing win again|