Croatia took the lead in the 18th minute when forward Ivan Perisic, one of five members of their starting line-up who played in the World Cup final against France, fired home a loose ball after it ricocheted around the Portugal defence.
Brazilian-born Pepe, handed the captaincy for the match, levelled 14 minutes later with a thumping header from Pizzi's cross.
Portugal rested all-time leading scorer Cristiano Ronaldo, still adapting to his move from Real Madrid to Juventus, while Sergio Oliveira and Sao Tome-born Gedson Fernandes won their first caps after coming on as second-half substitutes.
"We played well with a lot of young players trying to show their value," Pepe, 35, told RTP television. "I'm extremely happy. I'm grateful for the opportunity and everything Portugal has given me and I try to enjoy every moment."
A lively Portugal dominated the second half and nearly won the game when Mario Rui's low cross was deflected on to the foot of the post by Croatia defender Antonio Milic.
Croatia midfielder Luka Modric was applauded off the field by the home crowd when he was substituted in the 55th minute.
Croatia goalkeeper Danijel Subasic and striker Mario Mandzukic have announced their retirement from international football while midfielder Ivan Rakitic was rested for the game.
(Reporting by Brian Homewood, editing by Ed Osmond)
