32-year-old Onyewu was most recently playing for fellow Championship club Sheffield Wednesday, having moved to Hillsborough in January 2014.
His 12-year playing career has seen him turn out for clubs in Belgium, England, France, Spain and Italy, with his most consistent run of first-team football coming with Standard Liege. He is a 69-time capped US international, having played a starting role at both the 2006 and 2010 World Cup tournaments, and was voted the US Soccer Athlete of the Year in 2006.
However, his career has taken a downturn since leaving Liege in 2009, having made just 45 league appearances across six different clubs, failing to play a single game for AC Milan in a two-year spell, and also failing to appear for QPR between August 2013 and January 2014.
He has recently been on trial with Championship side Reading, staying with Nigel Adkins' men for three days, and appearing in a behind-closed-doors development squad friendly with Bournemouth - who won 2-1.
Having taken the lead through Pavel Pogrebnyak, the Royals fell to strikes from Ben Whitfield and Harry Cornick on Wednesday.
And it is now being reported by getreading that Onyewu has had his trial cancelled, and will not be signing a contract with the club.
With the club in the midst of an injury crisis, it is surprising to see the player not offered a contract. But clearly head coach Nigel Adkins did not see enough in Onyewu’s performances in training or match action to warrant a place in the Royals squad.