Lukaku returned to Stamford Bridge in a club-record £97.5million deal last summer on the back of two outstanding seasons under Conte at Inter Milan.
But the Belgian struggled to make an impact in Thomas Tuchel’s side, scoring just eight times in 26 League appearances, and returned to the Italian club on a season-long loan in June, with no obligation to buy.
Conte insisted Lukaku was a “good signing” for his former club but suggested he did not feel the love from Chelsea supporters as he did in Milan, when he was “the king”.
Conte said: “For sure, he [Lukaku] has the potential to play in the Premier League. I remember very well when he started to play last season, he played really well and you in the media said Lukaku is really strong. A lot of things can happen to drop [a player’s] confidence.
“I know for sure he is a bit disappointed with his impact, because he wanted to have another impact in England. But he has time. Now it’s right for him to play for an important club in Italy to try to get again confidence in himself. But we are talking about a really important, a really good striker.
“We are talking about a big amount of money [that Chelsea paid] for a player and I think we are talking about a really important striker in the world,” added Conte, whose side face Chelsea in west London on Sunday.
“But sometimes it happens a situation outside of football and I think Romelu lived two years in Milan and he was the king.
“The fans showed him a lot of passion and I think he’s a guy who needs this. And for this reason, I think he wanted to come back in Milan, but for sure, the signing was a good signing for Chelsea. Then, you know very well there are players that needed more time to make an impact, and maybe … but for sure he was a good signing for Chelsea.”
Conte’s Spurs finished fourth last season, a place behind their London rivals, but ahead of this weekend’s meeting, they are being widely tipped to overhaul the Blues as the capital’s top club and the most likely challenger to Manchester City and Liverpool.
But Conte believes his former club are still one of the strongest teams in Europe and the world, and says he cannot understand why they are largely being overlooked by pundits.
“I don’t know why [Chelsea are unfancied] because we are talking about one of the best teams in England, in Europe and in the world. Last season they won the Club World Cup,” Conte said.
“I’m sure Chelsea have potential, they are doing well in the transfer market, making good signings. The club is strong. I don’t understand why someone cannot believe in Chelsea. It’s difficult for me to understand.”