Thomas Tuchel believes veteran strikers Olivier Giroud and Edinson Cavani's fitness and self-discipline are behind the duo's success during the latter part of their careers.
France striker Giroud, 34, is part of Tuchel's arsenal at Chelsea and scored a magnificent overhead kick in midweek against Atletico Madrid in the first leg of their Champions League last-16 tie.
Meanwhile, 34-year-old centre-forward Cavani scored 30 goals under the German during the Uruguayan's final two years at Paris Saint-Germain, where he became the club's leading goalscorer of all time.
Cavani's move to Manchester United preceded Tuchel's arrival at Stamford Bridge by three months, but the former Borussia Dortmund boss was keen to highlight the quality of his past and current strikers in and around the box ahead of the two Premier League giants meeting on Sunday.
'Look at them and when they switch shirts, they are totally fit. Oli is 100 per cent fit, zero body fat, same as Edi.
'He is a player like Oli who, as a number nine, is always concerned about the team, suffers for the team, always ready to run open spaces and defend for the whole team.
'Then in the box they are both excellent finishers, they have the composure. They are top quality strikers, top quality number nines and for me their fitness and self-discipline are key to their success.'
Giroud continues to score important goals for the Blues and his return of six strikes in European competition so far is his best in a single season.
The wondergoal against Atletico took his tally for the season to 11, but despite his heroics in Bucharest, Tuchel refused to confirm if he would start against Ole Gunnar Solskjaer's men.
Asked if Giroud deserves to start, the German added: 'All the time. He trains very well, he is a big personality.
'Even when he didn't start he deserves to but I will not tell you today if he plays from the first minute.'