The Catalans are not worried by the Argentina attacker's inconsistency this year and are confident he will be back to his usual best in the Copa del Rey final
The Argentina international received some heavy criticism after Barcelona's Champions League exit at the hands of Atletico in midweek and again failed to impress at the weekend as the Catalans were beaten 1-0 by Granada.
Nevertheless, Zubizarreta has stressed the 26-year-old is feeling well at Barca and expects him to be back to his usual best against Real Madrid on Wednesday.
"There is nothing wrong with Messi. I do not doubt him even for half a second," Zubizarreta told TV3.
"We have been spoiled by what Messi has been doing over the years. We are used to seeing him doing magical things and deciding games from out of nowhere with his goals.
"He is physically well and is feeling great at Barcelona. He will definitely continue here.
"The last few results give little reason for optimism, but the Copa del Rey final awaits and Leo will bring us joy again."
Messi has scored 38 goals in 40 appearances in all competitions so far this campaign.