The details of the ex-Chelsea winger's deal in the Bundesliga is a topic of discussion for fans after Belgian loss
After scoring two goals in a 5-2 defeat to Switzerland, Belgian winger Thorgan Hazard, brother of Eden Hazard, is back on the agenda for Chelsea fans.
In 2015, 25-year-old left the Blues to join Borussia Monchengladbach on a permanent basis after a loan spell with the Bundesliga club. His comments at the time suggested that there was a buy-back clause inserted into the deal.
That has led some supporters to call upon their club to activate the agreement to bring Thorgan back to Stamford Bridge. However, the exact details of the contract were far from clear.
Speaking in 2016, Gladbach sporting director Max Eberl dismissed the idea of such a clause being in place.
"There is no clause," he told Express.de . "I do not want to comment on any contract content. But we also do not need to make any secrets about it.
"If we get such a top player from Chelsea, then Chelsea has, of course, always the opportunity, in whatever form, to think about this player."
In February, Sport Witness translated a report by SportsBILD that claimed that Chelsea have a right to match an offer if another club come in for Thorgan Hazard, rather than a straight buy-back clause.
"To be honest, even I don't know if there is one," said Thorgan in a recent interview with Onze Mondial .
"My father [Thierry Hazard] deals with that now. Sometimes, I hear there is one. Here, I'm told there isn't. Frankly, I don't know.
"It's not that I don't care, but I don't think about it. I'm happy here. If Chelsea want to buy me back one day, I think they'll do it, that's not an issue. Actually, if there is or isn't one, it's the same, really.
"If Chelsea want me, they'll pay for my transfer and they'll take me back. It's just a detail."
While Eden Hazard has come to be regarded as one of the finest players in Europe, and a Premier League player of the year, his brother Thorgan has grown into an impressive performer in his own right in the Bundesliga.
He has scored 28 goals and created 23 assists in the German topflight for Gladbach and has been linked with clubs such as Leicester City in recent transfer windows.
Eden Hazard is currently second in the race to be named Golden Boot winner in the Premier League this season with seven goals and four assists behind Sergio Aguero who has scored eight and set up four.
The older Hazard is still to commit his future to Chelsea, although it is hoped that he will sign a new contract in the coming months.
He also has a third brother in football. Kylian Hazard also plays for Chelsea and is currently on loan at Cercle Brugge.