Barcelona are looking for a new coach after they sacked Ronald Koeman with the Spanish giants ninth in La Liga and third in their Champions League group.
A dire financial situation has hung over the club in recent months, causing Lionel Messi to join Paris Saint-Germain in August. Barcelona are 1.35 billion euros in debt.
Any successor would have to work within those economic constraints, bring back a more attractive style of football and significantly improve results.
Most importantly, Barcelona president Joan Laporta will want to see greater assurances that the team will finish in La Liga’s top four. Failing to qualify for next season’s Champions League would only deepen the club’s financial crisis.
Xavi is currently in charge of Qatari side Al Sadd and would be a hugely popular choice with the Barca fans, given his glittering career at the Camp Nou as an elite midfielder.
There is also the belief that the 41-year-old would instil an attractive style similar to the one played by Barcelona when he was there under Pep Guardiola.
But Laporta has reportedly had reservations about appointing Xavi in the past, not least because of his lack of experience.
Xavi might also be reluctant to join, with the club in such a financial mess and now without his former team-mate Messi.
He is though the clear favourite to take the reins.
Gallardo has been manager of River Plate for seven seasons and long been touted for a move to one of Europe’s biggest clubs, including Barcelona.
The 45-year-old Argentine has won 12 trophies in his time in charge of River and believes in a modern, eye-catching playing style based on possession football and counter-pressing.
Hiring someone without coaching experience in Europe would be a risk, however, and it could also be difficult to persuade Gallardo to leave the Buenos Aires giants mid-season.
Ten Hag has become one of the most highly rated coaches in the world for his work at Ajax, taking them to two Dutch titles and a Champions League semi-final in 2019.
The 51-year-old Dutchman would continue a long tradition of moves between Ajax and Barca, with the clubs united by their adoration of Johan Cruyff.
Ten Hag is a disciple of attractive, possession football but he is also fiercely loyal to Ajax and is not believed to be keen on leaving after signing a contract until 2023 last summer.
Also has admirers in the Premier League, reportedly including Manchester United.