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The head coach can register just three of the seven new recruits for his Champions League squad, ahead of the last-16 tie against Borussia Dortmund, while even in the Premier League it will be difficult to keep players happy.
Chelsea has stars coming back from injury, to add to the sudden influx of fresh blood, and the onus is on Potter to shape a team that can win consistently after a stuttering start to his Blues career.
Owner Todd Boehly brought in Fernandez from Benfica on deadline day, with the World Cup winner joining the long list of arrivals at Stamford Bridge, after Chelsea also acquired Mykhaylo Mudryk, Benoit Badiashile, Andrey Santos, David Datro Fofana, Joao Felix and Noni Madueke.
Potter described Argentine midfielder Fernandez as "a fantastic player" and "an impressive young man", adding: "I'm excited by the second part of the season we have here, happy the transfer window's closed, and we can move forward and work with the players."
Chelsea had to inform UEFA about its squad choices for the Champions League knockout stage, and Potter said some players would inevitably be disappointed to miss out.
Loanee Joao Felix, fresh from arriving from Atletico Madrid, was described by Potter as being "in contention", but the coach would not commit any further on his choices.
"Of course, there's going to be a few awkward questions, that's the reality of where we are," Potter said. "A few awkward conversations because only 11 can play and only a certain amount can be in squads, so there's always going to be ones that are disappointed.
"It's about being as honest and open and transparent as you can and create an environment where you respect that people want to play, and respect the fact that players want to compete and help the team, but they have to be patient and make sure they're ready to play and perform and help us win."
Potter's Chelsea sits 10th in the Premier League, already 10 points behind fourth-placed Manchester United with 18 games left to play.
Its hopes of a top-four Premier League finish look bleak, but Potter will be expected to send Chelsea shooting up the table now he has ample resources.
"Everybody that's been in this room in the last four months, the word we've always spoken about is pressure, so that's not going to change," Potter said, speaking at Chelsea's press conference ahead of Friday's game against Fulham.
"Clearly, if you spend money, the external noise goes up. I understand that. Spending money is one thing, but you need to be able to align them, make the right decisions and provide a culture, a team, an environment.
"It's not the amount you spend on its own that gets success, it's more than that.
"Challenge is the right word, but I'm certainly not complaining about it. It's exciting. It's a test for me and the staff, but it's an exciting one.
"We've got a lot of really good players and we have to create an environment where there's healthy competition and they can push each other and understand there'll be frustration at times."
Potter says Chelsea have "tried to build something for the now and for the future", and he said he was "calm, calm" on deadline day as club officials negotiated to complete the Fernandez deal.
"I'm very, very pleased because we've got a fantastic player, and I'm looking forward to working with him," Potter said. "I spoke to him. My Spanish isn't great and his English isn't great, so we needed a translator, but we'll get there."
Hakim Ziyech's move to Paris Saint-Germain collapsed late on Tuesday, meaning he will stay with Chelsea, and Potter said the former Ajax winger would be "an important player for the rest of the season".