At least one German in the Allianz Arena was celebrating as Chelsea defeated Bayern Munich on their own turf to win the Champions League final. Marko Marin had just agreed to join Chelsea from Werder Bremen and, while his new team-mates rejoiced at their improbable victory last May, he looked on from his seat reflecting on a decision well made.

Whether it will work out for the club is open to debate, since Marin is a rarity: a Germany international in his mid-20s who looks like something of a gamble. A winger who can also play centrally, the 23-year-old made his Germany debut as a teenager in 2008 and Bremen paid Borussia Mönchengladbach almost £7m for him the following year. A similar sum has brought him to Stamford Bridge, indicating how his career has largely stalled.

Marin made two substitute appearances at the 2010 World Cup finals and appeared to belong alongside the likes of Mesut Ozil, Sami Khedira and Thomas Müller as totems of the new, young and thrilling German team. Yet he did not make the squad for Euro 2012, partly after missing much of the second half of the season through a hamstring injury and partly because he had not played well enough since South Africa to make himself essential.

A quick and enthusiastic dribbler, he has been denigrated as a provider of flair without substance. But he does not lack confidence. "It wasn't a surprise for me that Chelsea came in for me because all over the years there were a lot of big clubs interested in me. This time I thought it was the right step to go to England. It was a logical step," he said during Chelsea's pre-season tour of the United States. "Tottenham were interested in me in January but I decided early on that I wanted to come to Chelsea. It was not a choice for me. When Chelsea called I was sure I wanted to play there."

With the Brazil international Oscar set to join from Internacional for around £25m – the 20-year-old will complete his move after the Olympics, with the London club not anticipating any complications over a work permit for a highly-rated player who has been capped six times by the senior team – and Eden Hazard and Juan Mata already part of Roberto Di Matteo's squad, Chelsea seem well-stocked with nimble, attacking midfield players. They are also interested in Victor Moses, of Wigan Athletic, and looking at Hazard's brother, Thorgan, a midfielder for Lens.

Chelsea are likely to lose Florent Malouda, who has been linked with a move to South America, while Kevin De Bruyne and Romelu Lukaku may leave on loan, the latter having already stirred some interest with Fulham. Di Matteo described Oscar, who arrived in London on Tuesday with the Brazil Olympic squad, as "talented", but declined to add any details about Chelsea's interest.

"For me it's good to have technically-good players around me who can pass the ball, to have some guys who can give you the ball at the right time," Marin said. "I know I won't play every game. Nobody last year played every game."

He has two compatriots across London at Arsenal. "I know Lukas Podolski and Per Mertesacker well. It's nice to have some Germans around me," he said. While French and Spanish players have thronged to the Premier League, there have been relatively few Germans. "I don't know why there haven't been more Germans coming to England. In the last few years, Germans have started to move to other countries. Now there are a lot of good young players who are not afraid of taking the step to move to a different country. When Michael Ballack moved to Chelsea [in 2006] everyone in Germany was interested. Ballack was the biggest star in Germany at that time, the captain of the national team. So the Premier League was more in focus than before."

Now the scrutiny turns to Marin, for clues on how integral he will become to Di Matteo's plans, and whether he can sustain the pressure and make the transition from starlet to star.