Belgium midfielder was written off when he joined Tianjin Quanjian but two years later he is a vital cog in BVB machine

At least Axel Witsel was honest. “I don’t deny the economic aspect was important and my choice was made especially with the money in mind,” said the Belgium midfielder in November 2017.

A little more than a year on and now at the fulcrum of Borussia Dortmund’s revival following his lucrative spell with the Chinese Super League side Tianjin Quanjian that is thought to have earned him £20m in only 18 months, he can certainly afford to feel smug.

Written off in his homeland as a mercenary who turned down the opportunity to win titles with Juventus, Witsel has defied that criticism by winning his 100th cap against Iceland in October after excelling at the World Cup and has found a new lease of life since moving to Germany.

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He turned 30 last month and, usually deployed in the double pivot alongside Denmark’s Thomas Delaney in Lucien Favre’s fluid 4-2-3-1 system, has started all but one of Dortmund’s matches in the Bundesliga this season.

But while all the attention has been on the club’s emerging players such as Jadon Sancho, his fellow winger Jacob Bruun Larsen and the flying full-back Achraf Hakimi, Dortmund’s sporting director, Michael Zorc, believes the conductors of what has been described as BVB’s “modern jazz” approach – in comparison to Jürgen Klopp’s brand of “heavy metal football” – have been their midfield duo.

“We had the feeling last season it was too easy to beat us when a team scored against us. We had the feeling we couldn’t make it happen that we would win the game,” he said. “Therefore we chose some experienced, robust players; physically strong players but also with experience like Axel Witsel and Thomas Delaney from Werder Bremen.”

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From a team who were fortunate to scrape Champions League qualification ahead of RB Leipzig by goal difference and were soundly beaten twice by Wednesday’s opponents Tottenham in the Champions League group stages last season, Dortmund lead Bayern Munich by five points in the league despite throwing away a 3-0 lead against Hoffenheim on Saturday. There are dark horses to repeat Klopp’s run to the 2013 final in Europe’s premier club competition.

“One good example was when we played away in Schalke,” Zorc said. “If you compare the lineup to the one the year before there were 11 new players on the pitch. Just one year later. Then you can see the dramatic change in our squad.”

Facebook Twitter Pinterest Aexl Witsel excelled at the World Cup with Belgium. Photograph: Anadolu Agency/Getty Images

Yet despite making his debut in the competition as a teenager with Standard Liège in 2006, Witsel has had little success in the Champions League. Before this season, his last appearance came in Zenit St Petersburg’s defeat to his former club Benfica in 2016 and he has yet to go further than the quarter-finals having lost to Chelsea at that stage in 2012 with the Portuguese side.

His transfer to Benfica the previous year had been brokered by Luciano D’Onofrio – Standard’s part-owner at the time and Zinedine Zidane’s former agent – who was understood to have received a 10% share in the player as payment from Benfica.

Details of Witsel’s subsequent move to Zenit for his release clause of €40m were later revealed by the Football Leaks website, with the agent Jorge Mendes reported to have brokered the deal on behalf of D’Onofrio and Witsel’s father, Thierry. The Belgian newspaper Het Nieuwsblad claimed both had received up to €15m for helping to facilitate the transfer to Quanjian.

So for Dortmund to sign him for around €20m in the summer in the face of reported opposition from Bayern was almost as good a piece of business as their foresight in luring a 17-year-old Sancho from Manchester City in 2017. The Belgium manager, Roberto Martínez, described it at the time as “the best transfer in the world”. “What he brings to the team makes him the best signing of this transfer period,” added the former Wigan and Everton manager. “Dortmund deserve tremendous recognition for the signing of Axel. He had gone under the radar in China … I knew he would prevail.”

Having topped the Champions League pass statistics table for highest completion with 96% (he is second in the Bundesliga), Witsel has been making up for lost time. Dortmund last reached the quarter-finals two seasons ago when they were beaten by Monaco after a bomb attack on the team bus caused the first leg to be postponed for 24 hours.

If Tottenham are going to put the memory of their disappointing defeat by Juventus at this stage last season behind them, they will have to get past Witsel first.