Celtic captain Scott Brown has acknowledged his mistake in being sent off against Barcelona on Tuesday.
The midfielder was shown a red card a minute before the hour mark in the UEFA Champions League tie after kicking Barcelona forward Neymar.
Cesc Fabregas got the winner 17 minutes after his dismissal to move the Spanish side top of Group H and Brown admitted that the red card left the Scottish champions with an uphill task.
"I realise that I made a mistake in getting sent off," he said. "It's something that happened in the heat of the moment but I shouldn't have acted in this way," he told Celtic's official website.
"I still think it was a harsh decision. However, I recognise that I made a mistake and put myself and my team-mates in a difficult position. I need to live with that and there is no-one more disappointed than me about losing the match.
"There wasn't a huge amount of contact at all, to be honest, but I have to accept responsibility for my actions – and I do."
The defeat sees Celtic sit bottom of the group, having been beaten 2-0 by Milan in their European opener.
However, Brown felt that his team-mates deserved more from the game and remains confident that his side can qualify for the knockout stages.
"It was another fantastic performance from the lads after the Milan game, and although we've still to pick up a point from this group, we've shown we can compete against some of the best sides in Europe," he continued.
"We have four games to go in this group and everyone in the squad firmly believes that we can still qualify, and we are determined to get our first points on the board against Ajax in two weeks' time.
"The team deserved to get something out of the game after playing so brilliantly and putting in so much effort against one of the best sides in the world."
|5||V. van Dijk|
|Coach: N. Lennon|
for A. Stokes 70'
for M. Lustig 70'
for K. Commons 86'
|Higuain rejects extension from Napoli|
|Zamora returns to Brighton|
|West Ham can cope without Valencia - Gold|
|Wickham loses on Palace debut|
|Guardiola: No problem with Matthaus and Effenberg comments|
|Cartabia excited by Deportivo loan|
|Lyon confirm Rafael deal|
|Hysaj agrees deal to follow Sarri to Napoli|
|Rafael says his goodbyes to Manchester United|
|Dos Santos ready to get going with Galaxy|
|Pochettino rejects Soldado exit talk|
|Metatarsal misery for Mulumbu|
|Benitez: Benzema and Bale going nowhere|
|Mihajlovic: Ibrahimovic would make Milan title contenders|
|Hughes not taking any risks with Bojan|
|Guardiola relishing Audi Cup test|
|Di Maria ´taking a step up´ - Silva|
|Leicester bring in defender Benalouane|
|Deulofeu doubtful for Premier League opener|
|West Ham striker Valencia out for three months|
|UEFA: Qarabag-Celtic to go ahead|
|Palace seal Wickham swoop|
|Ronaldo and Benzema to miss Audi Cup|
|Marotta: Juventus could lose Pogba|
|Kante completes Leicester switch|
|Khedira ruled out for two months|
|FA accepts Mourinho criticism of Wembley surface|
|Robben rubbishes injury talk|
|Marchisio expects Milan title challenge|
|Rafael set for Lyon move|
|Celtic ´seeking reassurances´ over Qarabag pitch|
|Wenger beating Mourinho does not affect Chelsea - Zouma|
|Rooney moved by Everton welcome|
|Mancini not worried by lack of Inter goals|
|Coloccini wants to finish career at Newcastle - McClaren|
|Ramsey: Pressure to win trophies is nothing new|
|Terry: Wembley defeat could be a ´blessing in disguise´|
|Blatter not running for IOC re-election|
|Bendtner: Wolfsburg can challenge Bayern for Bundesliga honours|
|Liverpool relishing Britannia return, says Henderson|
|Everton big enough to keep Stones - Martinez|
|MLS Review: Fire stun Dallas as goals dry up|
|New Atletico signings excite Raul Garcia|
|Cahill expects Arsenal title challenge|
|Jovetic happy with Inter debut|
|Luis Enrique: Barca defence must improve|
|Yanev calls for calm after ugly scenes in friendly|
|Coppa Italia Review: Cittadella romp to victory, Brescia rely on penalties|
|Arsenal have learned how to play against big teams - Ramsey|
|Shawcross to visit specialist over back woe|
|Fiorentina 2 Barcelona 1: Bernardeschi double sends Barca to another defeat|
|Mancini hints at Melo interest|
|Rodgers hails ´incredible´ Benteke strike|
|Galatasary 1 Inter 0: Sneijder sinks former club|
|Wenger defends Arsenal approach|
|Wembley loss has no bearing on new season - Terry|
|Porto cruise to friendly win over Stoke|
|Mourinho denies Wenger ´snub´ suggestions|
|Arsenal abandoned their philosophy to win Community Shield - Mourinho|
|Mourinho throws Community Shield medal into Wembley crowd|
|Swindon Town 1 Liverpool 2: Benteke nets stunner on debut|
|Scottish Premiership Review: Hearts win thriller on top-flight return|
|Ujah at the double as Bremen beat West Ham|
|Mourinho: We were the better team|
|Wenger hails defensive solidity|
|Rooney returns as Villarreal spoil Ferguson´s party|
|Rodriguez stunner earns Southampton draw as Caulker makes debut|
|Arsenal 1 Chelsea 0: Case of 14th time lucky for Wenger against Mourinho|
|Taechaubol announces Milan agreement|
|Jojic fires Cologne to latest victory|
|China 0 South Korea 2: Kim and Lee seal victory|
|Origi getting up to speed|
|Costa a doubt for start of season - Mourinho|
|North Korea 2 Japan 1: Halilhodzic´s men spurn lead|
|Allam brands FA ´amateurs´ as name-change row rumbles on|
|Fournier ´worried´ by Lyon pre-season|
|Swansea still working on Michu exit - Monk|
|Neuer furious at Bayern Supercup defeat|
|Wenger: Ozil signing not a mistake|
|UEFA Champions League Preview: Shakhtar ready for Fenerbahce decider|
|Lampard targets MLS play-offs for City|
|MLS Review: Goals galore as DC United win 10-goal thriller|
|Ronaldinho returns and helps Fluminense to win|
|Keane: United won´t overtake Chelsea|
|Casillas has the ´enthusiasm of a 20-year-old´ - Lopetegui|
|Blanc hopeful over Ibrahimovic knee injury|
|Guardiola laments late goal in Supercup defeat|
|Tuchel plans to keep Bender|
|Hecking happy with Wolfsburg discipline after Supercup win|
|Arsenal players too interested in selfies and six-packs - Keane|
|Confusion over Ibrahimovic´s PSG future|