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."
|Brady: Patriots still have a lot of football to play|
|´No one died´ - Belichick´s message to Patriots after stunning loss|
|Silva lauds Digne after stunning free-kick|
|Aduriz joins Messi, Ramos in LaLiga history books|
|We have a plan - Ravens coach Harbaugh prepared for Flacco return|
|´It´s difficult to accept´ - Gracia calls for introduction of VAR|
|LaLiga press on with overseas match plan despite Barcelona withdrawal|
|PSG open Coupe de France defence at fifth-tier Pontivy|
|Hazard backs Sterling as Neville reveals England star´s Euro 2016 concerns|
|Everton 2 Watford 2: Digne salvages draw with 96th-minute free-kick|
|Barcelona could ´steal´ Kane, says Pochettino|
|Oakland Raiders fire general manager McKenzie|
|Struggling Villarreal appoint Garcia Plaza as Calleja successor|
|Warriors assign Cousins to G League team|
|Barcelona pull out of plan to play LaLiga game in Miami|
|Pochettino to keep an eye on Inter when Spurs face Barcelona|
|Pochettino confirms Walker-Peters set to start against Barcelona|
|Denver Nuggets add free agent Young|
|Topping Group A no magic wand for an easy knockout draw, says Simeone|
|The cake has been made, now we need the cherry - Ancelotti targets repeat at Anfield|
|Lloris braced to face ´one of the best in history´ in Messi|
|Tuchel expects Neymar to face Red Star|
|Foden signs Manchester City deal to 2024|
|It happened to me! - Valverde laughs off Dembele timekeeping|
|´Projecting´ an Argentina return? Messi met with AFA president and Scaloni|
|Erasmus expects to leave head coach role after World Cup|
|Chelsea issue suspensions pending investigation into Sterling incident|
|Kane is extraordinary – Valverde hails reported Barcelona target|
|Man behind Naomi Osaka´s rise wins WTA Coach of the Year|
|England name unchanged Test squad as Willey returns for West Indies ODIs|
|Spalletti: No issue with Icardi watching Superclasico in Madrid|
|Klopp confirms 2013 talks with ´chatty´ Napoli president De Laurentiis|
|Sri Lanka spinner Dananjaya suspended due to illegal action|
|His reaction was just brilliant – Klopp praises Sterling for response to abuse|
|Gomez renewal a ´smart decision´ for both parties – Klopp|
|Magnificent Molinari named European Golfer of the Year|
|Barcelona best option for Frenkie de Jong, insists midfielder´s father|
|Gronkowski on Miami Miracle: ´Got to make that tackle´|
|Tottenham youngster Walker-Peters signs on until 2023|
|Juventus ´more of a family´ than Real Madrid - Ronaldo|
|Kingsley Coman contemplates retirement if injury nightmare continues|
|McVay ´sick´ over offensive failings as Rams coach takes blame for loss|
|Calleja axed as Villarreal coach|
|Kenyan Drake on Miami Miracle: I couldn´t let Gronk tackle me!|
|Ronaldo: I deserved Ballon d´Or, the numbers don´t lie|
|Rugby Australia to make Cheika decision this month|
|England defender Gomez signs new Liverpool deal|
|Ronaldo wants to see Messi follow him to Italy|
|Neymar happy to play in any position for PSG - Draxler|
|Paine insists he is ´fine´ after taking blow to finger|
|Ponzio: River players will be ´idolised´ for Libertadores success|
|Champions League permutations: How Inter, PSG and Liverpool can progress|
|Kohli: India were better and deserved to win|
|Bears shut down Goff, Rams|
|India survive dramatic finish against Australia|
|Klopp calls for electric Anfield atmosphere against Napoli|
|Saints clinch back-to-back NFC South titles, Bears trump Rams|
|Bucks improve to 2-0 against Raptors with win in Toronto|
|Black Caps include Patel for Sri Lanka Tests|
|Maidana: River want Real Madrid clash|
|Cowboys top Eagles in OT behind stellar Cooper display|
|AC Milan evaluating Fabregas signing – Leonardo|
|WATCH: Steelers´ chance at game-tying field goal slips away|
|Hayne will plead not guilty to charges, says lawyer|
|Boca boss Schelotto: The only thing I feel is sadness|
|Cardinals´ Fitzgerald makes NFL history with most receptions for one team|
|River Plate´s Copa Libertadores star Gonzalo Martinez confirms January departure|
|Klopp: I was never worried about Salah´s form|
|Packers QB Rodgers sets NFL record for most passes without an interception|
|World Cup bulking hampered Man United form – Lukaku|