Sulc only joined Lyon last summer for 7.5 million euros (£6.4m), but his current club is already open to selling him for roughly three times that amount.
The forward made an immediate impact abroad with his impressive productivity. In Ligue 1, he recorded a tally of 11 goals and three assists and was directly involved in 21 goals across all competitions.
Given the financial situation of the traditional French club, which has recently been trying to stabilise by selling key players, Sulc is a hot candidate for a summer transfer.
Similarly, winger Afonso Moreira left for Leverkusen for nearly 30 million euros (£25.5m), having also joined Les Gones last year for a fraction of that sum.
The Plzen academy graduate has, according to sports journalist Santi Aouna from Foot Mercato, attracted the attention of several Premier League clubs with his performances.
Interest from Leeds is said to have led to concrete negotiations, during which Lyon set an asking price of around 25 million euros. However, no agreement has been reached yet.
Plzen would also benefit from this transfer thanks to a reported clause entitling them to 15 per cent of the profit from any future sale. If the Whites meet Lyon's demands, this would amount to 2.6 million euros (£2.2m).
In an interview with L'Équipe, Sulc previously admitted that playing in the Premier League is his dream. He was reportedly scouted over the winter by Nottingham Forest, Aston Villa and Tottenham.
He has also been linked in the media with Atletico Madrid and Como.
Until recently, Leeds also reportedly had Ladislav Krejci on their shortlist to strengthen their defence, but ultimately went in a different direction.
From Sassuolo, World Cup participant with Bosnia and Herzegovina Tarik Muharemovic arrived for £34 million.