The UK has abandoned the idea of having its Brexit "cake and eating it", European Council president Donald Tusk has said.
Mr Tusk made the comments as he left Downing Street talks with Prime Minister Theresa May.
He told reporters: "I feel cautiously optimistic about the constructive and more realistic tone in the Prime Minister's speech in Florence and of our discussion today.
"This shows that the philosophy of having a cake and eating it, is finally at an end... at least I hope so. That's good news."
The reference was a clear swipe at Foreign Secretary Boris Johnson who claimed Britain could have its cake and eat it over Brexit.
Mr Tusk said that not enough progress had yet been made in the Brexit divorce talks to move on to trade negotiations.
Describing Brexit as an exercise in "damage control", he said: "I feel now we will discuss our future relations with the UK once there is so-called sufficient progress.
"The two sides are working and we will work hard at it.
"But if you ask me, and if today member states ask me, I would say there is no sufficient progress yet. But we will work."
While posing for photographs with Mr Tusk at the beginning of the Downing Street meeting, Mrs May said the two leaders agreed that "things have moved on" in the Brexit process.
The PM stressed the need for a "good economic and security partnership" between the UK and EU after withdrawal.
She said: "I set out in my speech last week in Florence the hope for working together to that deep and special partnership I think we want to create with the European Union once we leave the European Union.
"And the commitment we have to looking for a really good economic partnership.
"I think that by being creative in the ways that we approach these issues we can find solutions that work both for the remaining 27 but also for the UK and maintain that cooperation and partnership between the UK and the EU."
The Downing Street meeting came after the fourth round of talks on the UK's withdrawal from the EU began in Brussels on Monday.
Brexit Secretary David Davis has insisted there are "no excuses" for blocking progress to trade talks.
The uncertainty surrounding Brexit is creating significant issues for many business areas but the implications for the life sciences sector are potentially far-reaching and fundamental. Ireland is the seventh-largest exporter of medicine and pharmaceutical products in the world and the sector employs more than 50,000 people directly.