In 2006, seeking to broaden his horizons and test himself abroad, Assoumani signed for German club 1. FC Saarbrücken, then playing in the Regionalliga Süd. His first season saw him feature regularly, making 32 appearances and registering one goal, though unfortunately Saarbrücken were relegated. Undeterred, he moved to Sportfreunde Siegen for the 2007/08 season and once again found consistent game time. He featured 27 times and scored twice, but again found himself part of a relegated squad.

After his second straight relegation, Assoumani left Siegen in the summer of 2008. A trial at Sheffield United followed, but ultimately no offer came. Undeterred, he caught the attention of Leeds United during a ten-day trial in December of that year. Managed then by Gary McAllister and pushing for a promotion push from League One, Leeds needed defensive reinforcements. After impressing in training and scoring a header in a reserve-team victory over York City, Assoumani was offered a one-month deal on December 17, 2008.

'He's looked good in training and settled in well and he'll come instantly into the reckoning for our game at MK Dons on Saturday,' McAllister said. 'He's played in France and Germany so he's got some good experience and, as he can play at right back as well as in the middle, he will give us more strength in the back four area. I watched him last night and I thought he did well. His goal was from a header and he took it well.'

Three days later, on December 20, Assoumani made what would be his only appearance for Leeds—an away match at Milton Keynes Dons. In a game that ended 3–1 against Leeds, he started at right-back before shifting to his preferred centre-back position at half-time due to a tactical change. Despite a brave display, the team’s defensive frailties persisted.

His contract coincided with a turbulent moment at Leeds. McAllister being dismissed immediately after the game, and Simon Grayson was appointed as his successor. Grayson, building a new defensive front, brought in Richard Naylor and Carl Dickinson on loan. Assoumani found himself surplus to requirements and was not included in subsequent matchday squads. His short-term contract was allowed to lapse, and he departed the club on January 18, 2009.

Ultimately, his solitary League One outing, sandwiched between time off the bench, became emblematic of the difficulties faced by loanees in shifting managerial environments .

Post-Leeds, Mansour undertook a trial with Crewe Alexandra late in January, though this did not yield a contract. It was Wrexham who would next sign him, bringing him into Welsh football on March 26, 2009, eting in England’s Conference National. He debuted on April 7 in a goalless draw against Histon, and quickly established himself as a regular, eventually racking up 40 league appearances and scoring once during the 2009/10 season.

In August 2010, Assoumani returned to England with Stockport County in League Two. Over the 2010/11 campaign, he featured in 36 league matches and scored a memorable goal against Macclesfield Town in September 2010. Despite giving his all, Stockport struggled and finished at the bottom of the table, leading to Assoumani’s release at the season’s close.

Following this, Assoumani decided to return to France, moving to semi-professional and regional clubs in the south. Between 2012 and the mid-2010s, he represented JS Saint-Jean Beaulieu, Le Pontet, Istres (briefly in the Championnat National), then again Le Pontet, before eventually turning out for RC Védasien and ES Grau-du-Roi later into his 40s. He also had the honour of representing the County of Nice in ConIFA internationals, winning the CONIFA World Football Cup in 2014, celebrating a lesser-known but emotionally resonant triumph.

Tracing the arc of his career, Mansour Assoumani shows the resilience and adaptability often required of journeyman defenders. His early years at Montpellier laid strong technical foundations, and the experiences in Germany added mental toughness. The arrival at Leeds, though fleeting, gave him a taste of English football in a demanding environment. Despite just one league appearance, that month at Elland Road exposed him to the rigors of promotions-driven ambition, shifting tactics, and managerial turnover.

Importantly, Assoumani’s signing under McAllister highlights the audition-based nature of short-term contracts. Scoring for the reserves, adapting across the backline, and earning a start shortly after endorsement aligns with the profile of a defender capable of groundwork under pressure. Yet his exit under Grayson shows how quickly such opportunities can evaporate when management priorities shift.

Even beyond Leeds, his performances at Wrexham and Stockport reflect a central defender committed to regular football, willing to step down leagues and apply his experience day in and day out. His solitary goal for Stockport and solid defensive displays stand as testament to his professionalism.

In aggregate, Assoumani’s story is a chronicle of hard-earned adaptability. From Ligue 1 heights to ConIFA glory with Nice, with chapters in German football, English league battles, and regional reflection, he offers a portrait of footballing persistence. His time at Leeds—while brief—captured the essence of transitional football careers: the mix of promise, timing, and circumstance. In just over a month, he experienced contract hope, first-team action, managerial change, and release—an intense microcosm of life on the margins of professional football.

As of 2025, Assoumani continues to embody the game’s enduring connections, still turning out in Regional 1 for ES Grau-du-Roi at 40, and bringing full circle a career rooted in love for the sport, regardless of level.