Chelsea came close to signing Brazilian attacker Taison 18 months ago, who was strongly linked with a switch from Metalist Kharkiv.
The forward eventually signed for Shakhtar Donetsk, to replace Willian, who moved to Anzhi Makhachkala.
While Willian switched to Chelsea last summer, Taison remains at his Ukrainian side, but potentially not for much longer.
His agent has revealed that enquiries have been lodged for his services from two Portuguese sides.
Manuel Carvalho told O Jogo: "This week there was an approach from Benfica and FC Porto, a small approach.
"The issue of insecurity has messed with the situation of Taison. As I said, this week Benfica made an exploratory approach, to learn values, but referred only to the loan of the player because Taison is expensive. But the situation in the country can benefit those interested."
Valued at £12 million, Taison is an affordable option for several Premier League sides, even if Chelsea do not have a direct need for him, unless they want to look at a back-up for Willian.
The 26-year-old winger scored four goals and provided six assists last season for Shakhtar, who face an uncertain short-term future due to political unrest in Ukraine.
Take a look at his finest strike here: