AEK's first home loss of the season was also the second-heaviest in the club's history.
"We have many problems which have not been solved," Jimenez told reporters. "What you saw is what we are at the moment; this is what happens with a small squad."
AEK, traditionally part of the 'Athens Big Three' with league leaders Olympiakos Pireaus and Panathinaikos, are languishing 18 points off top spot in fourth place.
President Stavros Adamidis revealed on Sunday he is wrestling with debts of over 31 million euros as he attempts to save the club from financial ruin.
"We must take brave decisions; it is our duty to save the team," Adamidis told Greek newspaper To Vima. "We took on a business that operated as if everything was fine while in reality it was sinking."
Olympiakos stretched their lead over champions Panathinaikos to seven points with a 1-0 win at Asteras Tripolis thanks to Spanish midfielder David Fuster's first-half penalty.
Olympiakos have 48 points and Panathinaikos could only draw 1-1 at rejuvenated Panionios, for whom on-loan striker Kostas Mitroglou, an Olympiakos player, scored his third goal in two games.
French striker Djibril Cisse continued his prolific form by notching the equaliser, his 17th goal of the campaign, for the Greens.
Coach Jesualdo Ferreira, however, has not given up on the title with 11 games remaining.
"We are not out of it yet. Definitely things are more difficult, but as champions and as a major club, you must play to win in all of your matches," he said. "Mathematically it looks tough, but we have to keep going."
