All eyes were on Serge Gnabry on Matchday 18. Making his return to the Weser Stadium, the Hoffenheim attacking midfielder had spent the 2016/17 season in Werder Bremen colours, helping the Green-Whites avoid the drop.

Most of those eyes watching Gnabry, however, would have looked on quizzically when they saw him emerge from the tunnel prior to kick-off: the 22-year-old came out with two mascots, not the officially sanctioned one escort.

The extra mascot was Lukas Bergmann, an 11-year-old from Bremen who has been battling leukaemia, with Gnabry's gesture fulfilling a long-held promise and continuing a longer-held friendship.

Watch: Click play on the video below for highlights of Hoffenheim's trip to Bremen

Gnabry's and Bergmann's is a special pact that dates back to October 2016. "That was when we received the crushing diagnosis," Lukas' mother, Anna, told deichstube.de. Then only 10, Lukas was consigned to hospitals instead of attending school and participating in sports with his friends. Tragically, his condition worsened soon after the initial diagnosis.

"We didn't know how long he had left and we really wanted at least to be able to fulfil his biggest wish: to meet Serge Gnabry," said Anna. A Werder fan, Lukas had taken a shine to Gnabry, who arrived in northern Germany from Arsenal in August 2016 and left an immediate impression at the club.

Upon hearing of Lukas' wish, a member of staff at the Hess Children's Hospital, where the youngster was being treated, got in touch with the club and asked them to pass the request onto Gnabry.

It didn't take long for Gnabry to come along, the then-Bremen midfielder visiting in February 2017. "Lukas was in such a bad state that he didn't even really realise what was happening," said Anna, whose son was soon after rushed to the intensive care ward.

Fortunately, Lukas came through. "The first thing he said [when he woke up] was that Serge had been to visit and had promised that Lukas would run out at the Weser Stadium with him," Anna said. "Serge had said that, but Lukas couldn't really have known. Even so, it was a reason that he fought so hard."

Soon after Gnabry's initial visit, however, the season came to an end. Bayern Munich signed the Germany international from Bremen, and promptly sent him on loan to Hoffenheim, where Gnabry fell off the radar somewhat after a series of minor injuries at the start of the season.

Having heard nothing from the player, the family assumed that would be the end of a brief, but fond, friendship. "We found out that Serge had the wrong number for us and had been trying to make contact," said Anna, who – amid the confusion – had written to Hoffenheim to try to get hold of Gnabry.

Her efforts worked. "On Boxing Day, Serge got in touch with us. Lukas was delighted and ever since they've been in touch regularly," Anna continued. Gnabry had not forgotten his promise, either, and ensured that when Hoffenheim visited Bremen on Matchday 18, Lukas would be alongside him.

And so he was. "It was just brilliant," Lukas said afterwards. "Serge asked me how I was getting on and gave me a signed shirt. I kept my fingers crossed for Serge and for Werder!" The 1-1 result, then, was perhaps the perfect outcome.

Gnabry (l.) in action against his former club on Matchday 18. © gettyimages / Lars Baron

Although it was an unforgettable day for the 11-year-old, it was also strenuous. While Lukas has left the hospital and is able to attend school every now and then, he is not yet fully recovered and the future, for now, remains uncertain.

"We just don't know," said Anna. "We can only hope. Lukas gets real strength [from moments like those with Gnabry] and we can only take our hats off to Serge for doing what he did. He's a fantastic human being."

Click here for the Werder Bremen vs. Hoffenheim MatchCentre