Wales can now look forward to a play-off final against the Republic of Ireland - winners over Georgia - after a night where they were once again inspired by Fishlock.
Wales were able to hit the ‘in case of emergency break glass’ button and pick their most-capped player and top goalscorer, who made her first start since suffering a leg injury for Seattle Reign on 9 September.
Morgan, who scored the goal that gave Wales something to cling to heading into this contest, also returned to the starting XI as Wales desperately sought to salvage their major tournament dream.
Wales struggled to retain possession and played in a style boss Rhian Wilkinson described as “frantic” in Poprad in their 2-1 first-leg defeat, but there was significant hope they could turn the tie around in front of a crowd of more than 10,000 in Cardiff.
Wales retained their shape with a 3-4-2-1 formation, with Alice Griffiths given the unenviable task of filling-in for cap centurion Sophie Ingle, who watched from the stands as she recovers from ACL surgery on her knee.
However, there was a familiarity about the opening exchanges as Wales dominated possession and looked to be positive but again lacked composure and quality when it came to the final ball.
Wales’ best opportunity in a tepid opening 30 minutes culminated in Rachel Rowe producing an air shot and Morgan dragging a shot wide, with goalkeeper Maria Korenciova untested and untroubled as she also saw a Holland effort sail over the crossbar.
Morgan was able to utilise her pace to stretch the Slovakian defence, but both a cut-back cross and a deft flick just failed to find Fishlock in space.
However, Fishlock is a tough women to keep quiet for long spells and on 38 minutes Wales made the breakthrough as Angharad James’ splendid pass bisected Slovakia’s defence and sent Fishlock clear to calmly chip the ball over the goalkeeper for her 46th Wales goal.
Fishlock might have doubled her tally just 60 seconds later after a tenacious piece of play from Rowe sent her clear, but this time her instinctive first-time effort was saved by Korenciova.
Morgan also had a late first-half chance to double Wales’ lead, but she took an extra touch as she raced clear and allowed Jana Vojtekova to make a vital block.
Morgan’s pace was a constant problem for Slovakia and she might have put Wales ahead on 47 minutes but fired over after cleverly beating her marker.
A minute later an even better chance arrived as Lily Woodham sent Morgan clear, but she blazed wide with just Korenciova to beat.