André Villas-Boas has accused Chelsea of playing "invisible" football and lacking style or identity since the days of José Mourinho as he prepares to return to Stamford Bridge for the first time since his sacking by Roman Abramovich last season.

The Tottenham Hotspur manager, who needs victory in Wednesday night's derby to fire his hopes of Champions League qualification, which could in turn thwart those of his previous employer, conceded that Chelsea had done "what matters" in modern football with their recent run of trophies.

Chelsea went on to win the Champions League last year after Villas-Boas's dismissal in March, not to mention the FA Cup, but it was clear that he felt they had made compromises in terms of their playing style which impacted on the achievement.

"In the end, it's brought them success and sometimes success is what matters in football – independent of the style," Villas-Boas said. "I have a different opinion. I think if you don't have a style, it makes you invisible in football. Only teams with style succeed. But, in the end, success is normally what matters in modern Europe."

Villas-Boas was asked to clarify what he meant by the comment regarding the "invisible" football. "Style of play … when things are attractive," he replied. "Obviously, what is attractive to me is maybe different to the style of football you might find attractive.

"We saw the wonderful team that Mauricio [Pochettino] is building at Southampton [at White Hart Lane on Saturday]. Although the change from Nigel [Adkins] to Mauricio is difficult to take because of what Nigel has achieved for that club, the reality is Southampton is not invisible in terms of their football. Their football is absolutely outstanding this season."

Villas-Boas's first spell at Chelsea between 2004-2007 saw him work as Mourinho's opposition scout, when the club enjoyed tremendous domestic success and, according to Villas-Boas, had a clear identity. He feels that it has since proved more elusive, and one of the reasons might have been the high turnover of managers.

Abramovich, the owner, has sacked five of them, including Villas-Boas, since he removed Mourinho, taking his total to seven. In addition, Guus Hiddink and the incumbent, Rafael Benítez, have worked on short-term contracts. Villas-Boas was endeavouring to impose his style on Chelsea only to be sacked after eight months. After his unveiling as Tottenham manager last summer, he said Abramovich had "quit" on him and failed to "put up to the things that he promised".

"If you remember, the [Chelsea] team of 2004 was an absolutely deadly machine of football but in a different way," Villas-Boas said. "[It was] great, great counterattacking football and one of the great teams in the country. There are various types of teams … teams built along great creative players and these Chelsea teams have the ingredient to be able to play this type of football. Barcelona with [Pep] Guardiola is probably the best team for playing football in recent years, in my opinion. But it changes from person to person."

Villas-Boas spoke in glowing terms of the abilities of the some of the players he worked with at Stamford Bridge, including Juan Mata, who was one of the signings that he pushed for, and Frank Lampard, who is one goal shy of equalling the all-time Chelsea scoring record. But he was almost matter-of-fact about the perception that Lampard had not supported him. "Yes, but his ability and quality was never in doubt," Villas-Boas said. "That [the lack of support] does not really matter right now. There have been other managers in this position before and, in the end, you study what you have done and become better and adapt. Only by learning from experiences are you able to deal with them better the next time."

Villas-Boas also responded to the Arsenal goalkeeper Wojciech Szczesny's claim that Tottenham did "not have enough quality" to finish in the top four. "I think it would be a little more tolerable if it had come from a genuine Arsenal fan," Villas-Boas said. "But it is coming from an Arsenal player, an Arsenal player who is probably only passing by to another club, or he's not going to stay there for life. In the end, does he mean exactly those words from the heart? He doesn't, for sure.

"He's entitled to say what he wants. It would be a little bit more realistic from a famous Arsenal fan to come forward with those words. From an Arsenal player, I don't think it has that kind of effect on us. I wouldn't say an Arsenal fan that has just arrived in that club in the last couple of years is entitled to have so much hatred towards Tottenham, like he seems to have."