Career
Youth career
Triantis" youth career began in 2009 at APIA Leichhardt Tigers before moving a year later to Sydney Olympic Football Club where he quickly forced his way into the First Grade squad. After amassing 49 games for Olympic and winning a title with them in the process, Peter was brought into the Sydney Football Club youth setup in 2012 under Brian Dene and impressed early in a pre-season youth tournament (2012 Vietnam Youth Cup) and then went on to play in the Sydney Football Club National Youth League squad. Sydney Football Club
Triantis made his A-League debut for Sydney Football Club on 22 December 2012 against the Newcastle Jets, where he came on as a 30th-minute substitute for Brett Emerton.
After being in and out of the team, Triantis received another start on 10 February 2013 where he scored his first goal for Sydney Football Club against Brisbane Roar.
The goal gave Sydney Football Club a 2–1 lead and turned out to be the winning goal. On 7 March 2013, Triantis signed a 2-year deal with Sydney Football Club and subsequently his first senior deal in professional football to take him through to the end of the 2014/15 A-League season with the club
At the start of the 2013/14 season, Triantis was ruled out for 4–5 months with osteitis pubis allowing Matt Thompson to sign as injury cover for the young midfielder. Triantis was released from his contract at the conclusion of the 2014-2015 season.
