Isma Goncalves says head coach Ian Cathro is capable of "amazing things" at Hearts but that it might take until next season for him to get it right.
Cathro, who took charge in December, has come under pressure after his side slipped to fifth in the table.
Goncalves worked under the 30-year-old at Rio Ave, where Cathro was assistant manager, in Portugal.
"I know how he works and, if you give him time, you will see amazing things here," he said.
"Inside of me, I am sure next season you will see what Ian is really capable of doing.
Hearts owner Ann Budge issued a statement on Thursday in which she stressed that Cathro was in charge of picking the team amid speculation about the role of former manager and present director of football Craig Levein.
Goncalves, who was signed by Cathro from Anorthosis Famagusta in January, insists that the Hearts players have confidence in the head coach.
"You can see there's a lot of pressure on him, but he has a plan he must follow to the end and must not change because we lost two or three games," said the 25-year-old striker.
"All the players trust him that his plan is going to work because we see in training what he is saying and what we do is clear and everybody is understanding what is his plan.
"I think every players trusts him and has confidence in him."
Hearts are five points behind fourth-placed St Johnstone and in danger of missing out on a Europa League qualifying place.
Cathro has suggested that, while he is aiming to qualify, his side might not be quite ready to compete at that level.
However, Goncalves believes it is hugely important that they qualify - even if it means a shorter summer break.
"With the plan the club have, it is important that we go to the Europa League," he said.
"Even if we had a holiday of six days or five days, I would be happy to have a holiday of a few days to play in the Europa League, or even not have holidays."
Hearts beat Dundee 1-0 on Saturday to end a run of three straight defeats.
"We needed a win and that's what matters," added Goncalves, he said ahead of Friday's trip to face Kilmarnock.
"We face this game with a lot of confidence to win it."