This time Dejan Lovren wants first impressions to last. It has not always been the case. The 24-year-old has had to overcome early ridicule in his professional and personal life to become what he is now: the linchpin of the Premier League's meanest defence and one of the signings of the season.

Lovren is loving life in England. Previous adaptations have been more traumatic, the worst coming in his childhood. His was one of millions of families affected by the war in the former Yugoslavia. When he was three, Lovren and his Croatian parents had to flee his Bosnian birthplace.

They found refuge in Munich and for the next seven years the young Lovren was "a happy boy, I spoke German perfectly, I went to school, I played for a little club." But the family were never granted permanent residency and when the German government deemed Croatia safe, the Lovrens were ordered to return home. It was a home that the 10-year-old Lovren hardly knew.

"It was two or three years before I was happy again," he says. "It was horrible at the beginning because the guys at school were laughing at me because I didn't speak Croatian well. I was speaking but they didn't understand anything I said. But after a couple of years it got better. I took the character from Germany and from my family because they were showing me that life is tough."

Once he made his reintegration successful, his football talent flourished. He eventually made it to the first team of Dinamo Zagreb, where he played in central defence alongside his hero, the former Liverpool player Igor Biscan. "He was my idol, I have great memories of playing with him," recalls Lovren in smooth English. But he was not so star-struck that he took his idol's advice when, in 2009, Chelsea tried to buy him. "He told me: 'You have to go to the Premier League, you will love it!" says Lovren, who instead joined Lyon.

"I was thinking maybe it will be much easier for me to play at Lyon than at Chelsea because they had [John] Terry, [Ricardo] Carvalho and so on," he explains. "I wanted to play and improve myself. I think it was the right decision. Maybe if I had signed for Chelsea I'd just have been sitting on the bench and what is the point in that?"

He will seek further vindication of his choice when Southampton take on Chelsea at Stamford Bridge on Sunday, though he admits the wisdom of his decision did not always seem apparent when he was in France, where for a while he was more bitterly mocked than the oft-lampooned Biscan ever was at Anfield. "The criticism started directly at the beginning and that was a difficult time for me," says Lovren. "I hadn't even arrived and they were talking bad about me just because of the amount they paid for me – €10m for a 20-year-old. I didn't speak French for one and a half years; I didn't understand anything and they didn't have the time to wait for me."

The French media's condemnation became so acerbic that after one performance – a 4-3 Champions League defeat to Benfica in 2010 during which Lovren played at left-back and scored a goal but was at fault for some of the opposition's – Lyon issued a press release to denounce journalists' "idée fixe" about Lovren and published statistics suggesting his display had not been as dire as reported.

But the perception of him did not really change even as he became a regular at the heart of Lyon's defence. And referees evidently took a dim view of his tackling: seven red cards in three years even led him to doubt himself. "I was thinking: 'Oh my God, what am I doing?'" he says. The answer, he reckons, is that he was not doing anything differently to what he has done at Southampton since the south coast club paid £8.5m in the summer to liberate him from Ligue 1. It is just that in England the referees are different. "I was the same player in France and I think now I'm showing the quality to everybody and proving, even to myself, that I was not so bad in France. I really wasn't."

Until illness led to him missing last week's defeat at Arsenal, Lovren had featured in every minute of Southampton's season, his central defensive partnership with José Fonte being one of the reasons why a once-leaky side is now the tightest in the top flight. Yet Southampton are not a defensive side; rather than sit back, they hunt the ball aggressively all over the pitch. Lovren says the club's statistics show that each player runs an average of 12km per game – that is over 2km more than Lyon said he ran in that Benfica match, where, according to Lyon's figures, he was the third most dynamic player on the pitch. Such vigorous pressing is also practised by Barcelona, whose guideline is that players must retrieve the ball within a maximum of six seconds of losing it. "Here it's two seconds," quips Lovren, who relishes his side's all-action style. "I was playing football in Lyon and Dinamo Zagreb but never like this. We play with risk but it's such a pleasure."

Few outsiders foresaw Southampton challenging for the Champions League places this season but the club's manager, Mauricio Pochettino, has repeatedly insisted there is no limit to the peaks his side can scale. Lovren agrees. "We just have to believe in ourselves and go get the points," he says.

No matter how the domestic campaign concludes, Lovren is confident his season will finish on a high. In the summer he is likely to be part of Croatia's World Cup squad. "For Croatians it means everything to play for the national team," he says. "Because of the past. A lot of people died in the war. It's like a duty for us to give everything." Lovren certainly does that.