It is rare phenomenon for Barcelona in the Champions League. Usually a free-scoring side in Europe, the Catalans have found goals harder to come by this term and improvement in that area could be key to their hopes of getting past Chelsea – and also to lifting the trophy in May.
Barca will be favourites to edge out the Blues and advance to the quarter-finals of the continental competition when the two teams meet at Camp Nou, but their shortage of goals so far will be one concern ahead of Wednesday night's big match.
Ernesto Valverde's side have netted only 10 times so far in this season's Champions League, with just two of those coming in the first half of games, while they needed a late leveller from Lionel Messi at Stamford Bridge to claim a draw in the first leg in London last month.
The Liga leaders hit three in a 3-0 victory at home to Juventus in the group stages, before beating Sporting CP by a single strike in Lisbon and then winning 3-1 against Olympiacos at Camp Nou. Two goalless games followed (away in Athens and Turin), prior to a 1-0 win at home to the Portuguese side and then the 1-1 draw in London.
That was a good result in the end for Barca, but it had not been their most dynamic display – particularly in attack, with Messi isolated for much of the game, forced to drop deep and Valverde's side extremely narrow – with four central midfielders and no natural width – in the centre of the park.
Valverde's view was rather different, however. "Despite what a lot of people said afterwards, I thought we played a great game against Chelsea," the Barca boss said later.
This Barca is built on firm foundations and it is that defensive stability that has helped the Blaugrana to remain unbeaten in La Liga, in which they have conceded only 13 goals in their 28 games this term.
However, they have also scored 72 (more than any other team) in the Primera Division and some of that form in front of goal would be useful in Europe as well – even though a goalless draw on Tuesday would see them progress to the last eight.
At Malaga on Saturday, Barca played with a more adventurous 4-3-2-1 system as summer signing Ousmane Dembele impressed along with January recruit Philippe Coutinho. But with the Brazilian cup-tied for the Champions League, that is not really an option in Europe.
Valverde is likely to stick with 4-4-2, but an increased role for Dembele could cause more problems for Barca's rivals and allow the Catalans to attack in a 4-3-3 formation. In addition, Paulinho and Ivan Rakitic will be expected to get into good goalscoring positions from midfield.
Jordi Alba and Sergi Roberto also play an important part from the full-back slots and with space to attack at Camp Nou, Chelsea are likely to find it more difficult to close the gaps to contain Barca like they did at Stamford Bridge.
Much of the responsibility, as usual, will rest upon the shoulders of Messi. And every time the Argentine has scored in the Champions League knockout stages since 2006-07, Barca have progressed.
Another plus, meanwhile, will be the return to form of Luis Suarez since the competition's group stages, although the Uruguayan is yet to score for Barcelona in Europe this season.
Valverde will hope that will change soon. Because although his side has only let in two in the Champions League in 2017-18, there will be more tough tests ahead in the latter stages, starting against Chelsea on Tuesday – and a few more goals would not go amiss.