The Liverpool forward, who is spending the 2018-19 season on loan with Derby County, sent a powerful, swerving effort into the top corner from outside the box to settle the contest in Dublin. Ben Woodburn was an unused substitute for Wales.
Elsewhere, Roberto Firmino, Alisson Becker and Fabinho helped Brazil defeat Argentina.
The Reds trio all featured in their country’s 1-0 friendly victory in Jeddah, with Firmino and Alisson completing the 90 minutes and Fabinho coming on early in the second half.
Simon Mignolet started for Belgium in their 1-1 friendly draw with the Netherlands - for whom Georginio Wijnaldum remained on the bench - while Naby Keita was substituted during the first half of Guinea’s Africa Cup of Nations qualifier against Rwanda.