Lukaku has endured a difficult time at Chelsea since returning to the club from Inter Milan for £97m at the start of the season.
The 28-year-old is no longer a guaranteed starter at Stamford Bridge and missed two glorious chances against Real Madrid in the UEFA Champions League quarterfinal first leg at Stamford Bridge after coming on as a substitute.
Lukaku has missed Chelsea's last two games through injury but is set to return to the squad for Sunday's FA Cup semi-finals against Crystal Palace at Wembley.
Werner has also not showed the kind of form he showed at RB Leipzig before joining Chelsea last season but he has impressed in his last two starts, scoring twice and hitting the post three times against Southampton last week and finding the back of the net again against Real Madrid on Tuesday.
Asked if Lukaku needs to emulate Werner if he is selected against Palace, Tuchel told a media conference: "For sure. He had a huge chance against Real Madrid [at home] and things can go so fast.
"Nobody knows what this goal would have done for us if he had taken his chance with the late header in the first leg.
"It is exactly what he needs to do. Wait, be patient, work hard and put the team first, be ready to help the team, because as a striker you can help within seconds.
"Especially for strikers, things can be turned around in minutes, in moments. Whole careers can be upside down and in any direction but always as a striker you can have a chance to put things into your favour, as a substitute or if you have the chance to perform from the beginning."
Chelsea will face Liverpool in the FA Cup final if they are victorious against Palace.
