Still smarting from a 3-0 defeat to the Netherlands in Geneva last March, Portugal fans were hoping for a morale-boosting win less than two weeks before they head to Russia.
But the defending European champions, who face Spain, Morocco and Iran in Group B, largely flattered to deceive.
Ronaldo and his goalscoring exploits would have been welcome in Braga, but the Portugal striker was given time off following Real Madrid’s 3-1 victory over Liverpool in the Champions League final on Saturday.
Portugal coach Fernando Santos gave Silva the nod and, despite a lack of playing time at Milan, the 22-year-old did well to head home the opener from Ricardo Quaresma’s pinpoint cross on 22 minutes.
It was the 1000th goal scored in Portugal colours.
Portugal doubled their lead on 34 minutes when Joao Mario, who has also endured a tough season in Italy with Inter Milan and a loan move to West Ham, pounced on a poor clearance from a corner to fire a rocket into the top corner from the edge of the area.
Strong and physical throughout, Tunisia were sorely lacking technique and attacking prowess.
But when the disappointing Raphael Guerreiro fluffed his lines, Esperance striker Anice Badri reduced arrears just before the interval.
Portugal continued to dominate but after Bernardo Silva fired wide the hosts paid the price for loose defending when Fakhredine Ben Youssef hit a 64th minute equaliser.
Portugal are likely to still be without Ronaldo when they face Belgium in Brussels on June 2 and Algeria in Lisbon on June 7.
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