Equally comfortable on the wing or in attacking midfield, Willian signed for the Miners as an inexperienced and inconsistent 19-year-old after an impressive start to his career with Corinthians and, although his debut season included prolonged periods on the bench, he has since gone on to become an integral part of the first team.
The Brazil international was the subject of concrete interest from the Blues in January, and his boss admitted that the attacker would be allowed to leave if price is right.
Lucescu told Romanian TV station Dolce Sport: "I told Willian he can leave, but only if the right offer is made. He's a great player.
"Willian was the biggest investment Shakhtar have made in a young player, we have to respect that. He played only seven or eight games in Brazil."
The Romanian also questioned Chelsea's judgement in regards to player ability, highlighting the big-money move for Belgian star Eden Hazard, and confidently suggested that the tricky Brazilian is superior to the two-time Ligue 1 Player of the Year.
He continued: "They paid a lot of money for Hazard but are not willing to pay for Willian, even though he's better in my opinion."