After watching his side lose to arch-rivals Real Madrid in the Supercopa de Espana final, Segura let it slip that Barca "expect" to seal the arrivals of both attackers before the summer transfer window shuts.
Barcelona have been chasing the duo ever since Neymar left the club in a record 222-million-euro move to Paris Saint-Germain.
"We are close to Coutinho and Dembele", he said on Catalan television station TV3. "We know it is a tough game".
And, while Jurgen Klopp's side remain adamant that the Brazil worldwide is not for sale at any price, Dortmund have also moved to dismiss the reports and in the process mocked Barca for being beaten 5-1 by Real Madrid in this week's Supercopa .
"I don't even know them". "We have to help the team".
The player submitted a transfer request last week, after Liverpool rejected two bids from the Spanish club.
"Dembele and Coutinho are two important players that we like a lot and have done for a long time. I have never met him", Klopp said.
"I don't know why other people are saying what they are saying. No news. Nobody has told me any different".
Reports in the Spanish press have suggested Coutinho would be willing to go on strike in order to push through a move to the Nou Camp.
Philippe Coutinho will not appear against Palace and is continuing to sit out training sessions with a back problem.
"If, for example, there is an offer for a player and I say "No" and the owners say, "Yes, let's ask for a number on how much they want to pay.' And I say, 'I don't want to hear it". We are all not silly.
"We are not silly, we know it is a very hard situation - but there's nothing new to say". I will try to do my job and I am prepared.
Dortmund have turned down an identical offer for their France global Dembele, who is now serving an internal suspension at the German club after missing training amid the speculation surrounding his future.