Following yet another season of overachieving with underdogs, Pena received attention from Europe. Belgian side Mechelen gave him the role at the helm of their club in December 2023, having parted ways with their previous manager due to mutual consent. The Belgian side was sitting in 8th, an ideal position for their team and so there was worry about a manager without European experience destabilizing the side.

Transfers in:
Oni 71 from free agents
Letica 72 from CFR Cluj (2.5m Euros)
Ojo from Aberdeen (750k Euros)
=3,25m Euros

Transfers out (all in January):
Abdallah Mrabti 72 to Birmingham City (2m Euros)
Valerberghe 73 to Lens (6m Euros, release clause activated)
Couke 70 to Genk (2.8m Euros)
=10,8m Euros

Performances:
Belgian League: 2nd (after both the normal league season, and play offs)
Belgian Cup: final