Antonio Conte expressed regret that Kevin de Bruyne will be turning out in the light blue of Manchester City rather than the royal blue of Chelsea on Saturday.
The 25-year-old Belgium playmaker was offloaded in January 2014 after being a peripheral figure under Jose Mourinho before thriving at Wolfsburg.
City signed him for £55million after 18 months in the Bundesliga and De Bruyne will be in opposition when Conte's Premier League leaders face a stern test of their credentials against Pep Guardiola's City.
"I think he's a really great player. It's a pity that now he's playing for another team," Conte said.
"I wish for him the best, (but) after our game."
Chelsea have plenty of options without De Bruyne. The attacking triumvirate of Diego Costa, Eden Hazard and Pedro have been in fine form of late.
Costa has scored 10 times this season and Conte has lauded his contribution.
The Spain striker has often appeared distracted by antagonising the opposition and officials, but now he is punishing defences.
"Diego is showing great respect, great passion in the right way," Conte said.
"I remember at the start of the season the only questions about Diego were 'this passion is not good, try to change his behaviours, his attitude'.
"I think Diego is playing very well. His attitude and behaviours are fantastic. Now it's important to continue in this way."
Conte also praised Guardiola's role at Manchester City. Like the Italian, City's Catalan boss is in his first season in the Premier League.
It will be the first time the pair have been in opposite technical areas as managers and Conte is uncertain if they played against each other when Guardiola briefly played in Serie A with Brescia and Roma.
"I think he's a fantastic manager and he's doing fantastic work with Manchester City," former Juventus midfielder Conte said.
"When you see this team, I recognise an idea of football. Tomorrow for us, it'll be a very tough test.
"I don't remember if we played against (each other). He was a fantastic midfielder. We had different characteristics.
"He was more a pivot in front of the defensive line. Me, I was more offensive with penetration.
"I think that I ran more than him. But he thought more than me, with the ball.
"Two good players in their career won a lot and also lost a lot for me. I won a lot, but I lost a lot of finals."
Chelsea could name the same starting XI for the seventh successive league game.
Conte said there were doubts over one or two players, but declined to disclose their names ahead of his side's bid for an eighth successive win.
Chelsea have conceded just once and scored 19 times since Conte adopted a 3-4-3 formation which has seen wins over Hull, Leicester, Manchester United, Southampton, Everton, Middlesbrough and Tottenham.
"Tomorrow is a great test for us, for our formation, to continue in this way," Conte added.
"We know that it won't be easy because tomorrow we face a really great team.
"We want to show we are working very well and we are growing. Tomorrow is another step to show us if something changed compared to the start of the season."