The Bluebirds included three trialists in their under-23 development team against Watford at Cardiff City Stadium.
The result was a 1-1 draw in their Professional Development League Cup group.
Scottish midfield player Scott McLean, who plays for Troon, joined fellow trialists Jake Evans and Danny Rowe in the Cardiff team.
Former Kilmarnock player McLean, 20, has had a spell on trial with Livingston and is now spending 12 days in South Wales.
“I’m playing in a couple of matches and they will make a decision on whether I am offered a contract or not,” said McLean, who is from Ayr.
“I’d love to play in England and it would be a good opportunity to showcase myself at a big club.”
Troon manager Jim Kirkwood says: “It’s good that Scott plays for our club and has a chance for trials at Cardiff City and Livingston.”
Swindon-born teenager Evans is a midfield player who started his career with his home town club and played first team football. He had loan spells with Waterford and Farnborough, the Southern League Premier Division club he now plays for.
Rowe is a neat and tidy young midfield player who completed the 90 minutes. He is a former Leicester City winger who moved on to Queens Park Rangers and signed a senior contract.
Rowe and QPR parted company last month by mutual consent.
He produced some good work wide on Cardiff’s left and picked out teammate Rhys Abbruzzese, who crossed first time. Ibrahim Meite’s initial close range header was saved by goalkeeper Sam Howes. When the ball ran loose Meite lashed it at goal again.
Howes stood tall and blocked again.
Nigerian-born substitute Ogo Obi, 20, fired Cardiff soon after replacing injured Meite.
Obi’s goal went in after 75 minutes and moments later he almost added a second, powering towards goal and firing low across goal. His fierce effort only just flew wide.
Mark Harris went close for Cardiff when his shot from 25 yards was blocked and the ball looped high into the air before bouncing off the Watford crossbar.
The Hornets included Jerome Sinclair, their £4m signing from Liverpool in 2016. Sinclair was 16 years and six days old when he made his Liverpool debut and is their youngest ever first team player.
Watford also included winger Dion Periera who has senior experience with the Premier Division club.
The visitors equalised during injury time when Cardiff stopped an attack and the ball ran kindly for Ashley Charles, who fired into the corner from 20 yards.
Cardiff City: Warren Burwood, Cameron Coxe, Rhys Abbruzzese, Danny Rowe, Ciaron Brown, Paul McKay, Ibrahim Meite (Ogo Obi 68), Jacob Evans, Mark Harris, James Waite (Lloyd Humphries 61), Scott McLean. Subs not used: George Ratcliffe (gk),Adam Sharif, Ben Margetson.
Watford: Sam Howes, Ben Jones, Lewis Gordan, Ashley Charles, Max Ryan, Joy Nukena, Dennon Lewis, Carl Stewart, Jerome Sinclair (Ryan Cassidy 62), David Sesay (Reece Stray 90), Dion Periera. Subs not used: Nathan Gartside, Jesus Cruz Cabrera.
Referee: Savvas Yianni.