The Spaniard was talking about his striker Romelu Lukaku after seeing the Belgium international return with a goal in the 1-0 win over West Ham.
Lukaku emerged from the bench to help the shot-shy Toffees see off a dogged Hammers outfit by converting Leighton Baines' cut-back to hand his side a precious 1-0 win in their chase for a Europa League spot, at the very least.
And Martinez believes the Belgian is so pivotal to his side, who have toiled in his absence, that he has compared his presence in the team to that of Lionel Messi's at Barcelona.
Following the match, Martinez told reporters: "Lukaku is an irreplaceable footballer and that is a reality."
"Barcelona are one of the best teams in the world but when they have not got [Lionel] Messi, the team suffers."
Lukaku may not be plying his trade at Goodison Park next season of course, with Chelsea manager Jose Mourinho expected to recall the striker to his parent club in the summer.
But irrespective of the 20-year-old's future, Martinez is hoping his current roster of loan players can leave their mark during their respective stays on Merseyside.
"All I want is for the boys that we have on loan is that they have an incredible experience as players," he added.
"Some of the young ones just to develop, Gareth [Barry] just to have a real enjoyment and create memories for the future.
"The loan market is very important for us. If we can keep those players great, if not then we will have to use the loan market again."
image: © wshjackson