Brazil playmaker Willian was left bitterly disappointed this summer after Shakhtar reportedly snubbed bids from both London clubs.
And the 24-year-old revealed he would welcome an approach from either when the transfer window reopened.
"There were two offers in the summer," he told Lancenet.
"One from Chelsea and one from Tottenham. Choosing between the two clubs would be difficult. I don't know."
Spurs boss Andre Villas-Boas was in charge at Chelsea when they saw a £16.7million bid for Willian knocked back in January.
Willian said: "I mean, Tottenham is a big club and it has a good person in charge. Andre Villas-Boas wanted to bring me to Chelsea and also tried at Tottenham.
"He always sends me messages. We are always in touch, and he has become a friend, for sure. And Chelsea is Chelsea. They are a great team, with amazing players and are the champions of Europe."
Willian, who is expected to start Shakhtar's crunch Champions League match against Chelsea tomorrow [Tuesday] night, added: "I would love to play for either of those clubs. But my mind remains at Shakhtar, and I'll do my best to get the win against Chelsea.
"Everybody knows what my goal is. I've clearly stated that I would like to play in a bigger stage, whether it be England, Spain or Italy.
"I want to come back to the national team, and being in a bigger spotlight would help me get noticed."