Antonio Conte felt Chelsea were close to delivering a "perfect" game against Barcelona in the Champions League before Lionel Messi's leveller salvaged a 1-1 draw for the Catalan giants.
Willian, denied twice by the woodwork in the first half, gave the Blues the lead after 62 minutes with a pinpoint rifled drive from the edge of the penalty area.
Chelsea looked set to hold firm against Barca and take a one-goal lead to March 14's return game at Camp Nou, only to shoot themselves in the foot.
Andreas Christensen gave up possession with a sloppy pass deep in his own half, Andres Iniesta feeding Messi to score his first goal in nine appearances against Chelsea.
Conte was left frustrated by Chelsea's failure to close out the victory, Messi striking with 15 minutes to go from his only shot of the game, yet the Italian was delighted with the way his team delivered a defensive masterclass - barring one costly slip.
"I think we were very close, very close to a perfect game," Conte told BT Sport. "I think only one mistake and when you make a mistake against Barcelona, players like Messi, [Luis] Suarez, Iniesta, you have to pay.
"It's a pity, I'm very proud of my players for the game, they followed our plan. It's a pity. It's a pity because also I think tonight we were a bit unlucky.
"I think when we have to have a plan for this game, respect the characteristics of the opponent and understand the best way to face them. Our plan was really really good and the effort was great, it's a pity because we are talking about 1-1 and maybe we deserved more tonight."
Barcelona's away goal gives them the edge ahead of next month's second leg but Conte believes Chelsea can cause an upset when their rivalry renews with the Catalans at Camp Nou.
"This team is very strong, a fantastic team, but I think the result means the tie is open," Conte said.
"It will be difficult, it's not simple to play away against them, but our performance will give us confidence to try and do something."
Barcelona recorded over 72 per cent possession at Stamford Bridge but captain Iniesta is not expecting the second leg to follow a similar pattern.
"The match has had everything. A match of champions," the veteran midfielder told TV3. "Very intense in front of a great team. We knew it was going to be difficult.
"At home I think the game will be different . Playing at home with our people, we know the field better and the game will be different. But come on, we know it will be complicated because they will play everything.
"They are one of the best teams in Europe, they have great players and this is the Champions League, everything is complicated here."
|Chandimal appeal against ban rejected|
|Real Madrid sign teenage goalkeeper Lunin|
|Serbia 1 Switzerland 2: Shaqiri strikes late to clinch crucial comeback victory|
|Suspended Srna joins Serie A side Cagliari|
|Cilic sets up Kyrgios showdown as Djokovic reaches milestone|
|Kudla up next in Federer´s Halle ´fight´|
|Assistant Farbrace to take charge of England for T20 games|
|Hummels hoping to be fit for Sweden clash|
|Hend surges clear as Fleetwood struggles again in Pulheim|
|Giant-killers Mexico embrace sudden weight of expectation|
|Roma complete €17.25m Kluivert deal|
|Pakistan name strong group for Zimbabwe tour|
|Choc Horror: Boullier insists McLaren do not hand out Freddos as bonuses|
|Neymar: Not everyone knows what I went through|
|Poland v Colombia: No time to dwell on regrets, warns Aguilar|
|Musa shows Messi how it´s done to set up critical Argentina showdown|
|Nigeria 2 Iceland 0: Musa brace boosts Super Eagles & Argentina|
|McLaren and Renault open to Ricciardo talks|
|We must win, we have no other choice - Maaloul|
|Germany will respond against Sweden, insists Low|
|´The best among all Asians´, South Korea trust in Son against Mexico|
|Stalin´s bunker an unlikely site for Russia´s World Cup charm offensive|
|England v Panama: Rashford tipped to start as Southgate´s side aim for last 16|
|Erasmus wary of ´wonderful´ Cipriani|
|Hummels to miss Germany-Sweden, confirms Low|
|Murray accepts Eastbourne wildcard|
|St Petersburg madness lines up Neymar and Brazil with heroes of the past|
|Martinez happy to be ´boring Belgium´|
|Japan v Senegal: Squeaky clean Group H rivals eyeing huge step towards last 16|
|Argentina team the worst in history - Ardiles|
|Ravanelli upsets wife by taking Arsenal job...in Kiev|
|Federer moves a step closer to 10th title in Halle|
|Brazil 2 Costa Rica 0: Coutinho and Neymar score in stoppage time to snatch win|
|Andersson: Sweden embracing big occasion as bug sweeps through team|
|LeBron in ´good dialogue´ with Cavaliers|
|Ronaldo will always be the best, Fonte claims|
|Southgate criticises press for England team leak|
|O´Mahony: Series win in Australia would be up there with Grand Slam|
|Khedira thrilled with Can capture, staying with Juventus|
|Samuel open to Higuain-Icardi swap deal|
|It´s just a game - Milligan disappointed by Kruse criticism|
|From drug-testing lab to gastro pub: Sochi happy not to forget dark past|
|Ronaldo will do what is best for him, says Carvajal|
|Kohli: India will feel at home in England|
|Barca target Lenglet yet to decide future|
|Germany perform best under pressure, Klose claims|
|Juanfran signs one-year Atletico Madrid extension|
|Julian Nagelsmann: The remarkable rise of RB Leipzig|
|Sterling: my daughter is Liverpool through and through!|
|Van Bommel to take charge of PSV|
|Hansen urges France not to ´squeal´ over decisions|
|Intelligent Jones will turn England´s fortunes around - Moody|
|Nainggolan confirms imminent Inter transfer|
|U.S. Open missed cut may be blessing in disguise - McIlroy|
|Schmidt in no rush to decide on his future|
|Wallabies treating decider as grand final - Hooper|
|Salah won´t leave World Cup, Egypt FA boss claims|
|Chandimal, Hathurusinghe and Gurusinha admit ´serious´ conduct breach|
|Mikal Bridges´ 76ers dreams dashed in dramatic draft twist|
|They want to pull you down - Sterling hits out at tabloid press|
|Lazaridis wants West Ham to stick with Mexico star Hernandez|
|Get behind Sterling, urges Henderson|
|Sampaoli begs for Argentina´s forgiveness|
|The 2018 NBA Draft first round in full|
|Everything still to play for against ´very strong´ France, says Eriksen|
|Cubs bested by Harvey, Yankees sweep Mariners|
|Spurs GM: We´ll do what we can to keep Leonard|
|Lovren: This Croatia team are better than 1998 heroes|
|Internationals Musa, Okobo selected in NBA Draft|
|Modric is the world´s best number 10 – Arbeloa|