Mertens didn't fancy another attempt. So 20-year-old midfielder Amadou Diawara stepped forward. History was against him; the likes of Lionel Messi, Zlatan Ibrahimovic, Neymar and Radamel Falcao had all fluffed spot-kicks against Pep Guardiola's side in the Champions League.
But there were no nerves from the Guinean. He slotted his penalty into the corner, grabbed the ball and pounded his chest as he returned to the centre circle. It was a rallying cry from the young man who had just struck his first professional goal.
A second never came for Napoli in the group stage clash but Diawara had made an impression. And not for the first time.
“I took the ball from Marek Hamsik and asked Mertens for permission [to take the penalty],” he said “That penalty was the first goal of my career and I am very happy to have scored it. But naturally I’m disappointed with the result.”
The mental strength and fighting spirit Diawara showed by taking that penalty defined his early career. Born in Guinea, he was brought to Italy at the age of ten and joined the youth academy of lower league side San Marino, where his talent was spotted by the great sporing director Pantaleo Corvino a few years later.
Corvino – who uncovered players such as Mirko Vučinić and Stevan Jovetić – was impressed by the power and quality of the youngster during a training camp in Lecce.
When Corvino joined Bologna, he kept a promise to bring Diawara with him and it did not take long for the midfielder to make an impression. By then he had turned 18 and he instantly became a first-team regular for the Rossoblu, with scouts from across Europe soon making trips to the Stadio Renato Dall’Ara and leaving with notebooks crammed with positive opinions.
Schalke and Eintracht Frankfurt reportedly made offers in the region of €12million during those early months, only to be told the Emilia Romagna-based club believed he would soon be worth much more.
One season and 34 appearances later they would be proven correct. A raft of big clubs expressed their desire to secure his services as the 2015/16 campaign drew to a close.
“There is a strong interest from Chelsea,” Diawara’s agent Robert Visan admitted during an interview with TuttoMercatoWeb.
“I work with Pini Zahavi, who everyone knows, but that does not mean that will he will go to Chelsea. The likes of Manchester City, Tottenham Hotspur and Juventus follow him but with them I never speak of offers, only football.”
Corvino and Bologna took an aggressive stance, only to see their leverage undermined when Diawara refused to report for pre-season training and insist he wanted to join Napoli.
Eventually the club relented and sold him for €16million, a tidy profit on their meagre €420,000 outlay just twelve months earlier. Yet rather than a sign of immaturity, it seemed the hold-out was simply a player getting exactly what he wanted from a situation, much like his idol has done in the past.
“I really like Yaya Tourè,” the man who wears the no.42 shirt in honour of the Ivorian told La Gazzetta dello Sport. “I’m inspired by him and I would love to follow his trail. Quality has no age, I'm working hard to get to my dreams.”
Soon he was back on the pitch and his performances were bearing much more resemblance to Claude Makélélé than the former Manchester City captain. Over the course of 2016/17, he averaged 2.2 tackles and 2.3 interceptions per 90 minutes, providing a robust shield to the defence while playing a full role in Napoli’s intricate passing game.
This term, across Europe’s top five leagues, only Marco Verratti and Napoli’s Jorginho (both 106.4) have averaged more passes per 90 minutes than Diawara’s tally of 106.1. Due to the presence of his Brazilian-born team-mate he has been largely used as a substitute in Serie A, but in Europe he has been given time and space to fully showcase his ability.
That began last season, with his performance in the Champions League last-16 clash with eventual winners Real Madrid, arguably one of his best displays to date.
Standing 6ft and powerfully built, his tactical understanding and intelligence have come to the fore under the tutelage of Maurizio Sarri, the veteran coach has taught him when and where he should be at all times.
Given his impact in a reserve role, talk of another move has unsurprisingly begun, with Tottenham Hotspur once again taking a long look at the 20-year-old.
According to the Corriere dello Sport, the English side have already held talks over a €25million move, although Diawara’s agent has denied the presence of a release clause in his current deal.
Paid just €750,000 per year net and with three years remaining on his contract, he is due a hefty rise in salary, something Napoli – whose top earners only receive €3.5million as they operate within a strict wage structure – may well be reluctant to do.
Should he decide he does want to move on, Diawara has already proven that, much like with Champions League penalties, he is unafraid to take destiny into his own hands.