Former Birmingham striker Christian Benitez has died at the age of 27.
The Ecuador international, who had just joined Qatari side El Jaish Sports Club, spent the 2009-10 season on loan at St Andrew's from Mexican side Santos Laguna.
Benitez, who won 58 caps for his country, played in El Jaish's 2-0 win over Qatar Sports Club on Sunday.
He returned to Santos Laguna in 2010 after Birmingham opted against a permanent deal for him.
El Jaish, who signed Benitez, also known as 'Chucho', on 6 July, confirmed the news but the official cause of his death is unclear.
Their statement said: "The club would like to offer its sincere condolences to the family of the player.
"Benitez had recently joined the club from Club America for three seasons. The player participated for the first time with the team during yesterday's match against Qatar Sports Club in the Sheikh Jassem Cup without complaining of any health problems.
"His sudden departure is a big shock for each member of the technical and administrative staff. He was a player that over the short period he was here was regarded for his high moral character."
Birmingham will mark the player's death ahead of Saturday's Championship match against Watford at St Andrew's.
A statement from the club said: "The thoughts of all associated with the club are with Chucho's family and friends at this very sad time.
"The Ecuador international was an immensely popular character during his time at the club."
Former Republic of Ireland midfielder Lee Carsley, who was a team-mate of Benitez at Birmingham, told BBC Sport: "It's devastating news for his family and I'm sure Birmingham City will want to pay their respects.
"I remember he had outstanding ability, was very quick and was a bit of a free spirit.
"He had a big personality and he burst on to the scene when he came on at Old Trafford [as a substitute against Manchester United in August 2009] and caused lots of problems. His ability - and goalscoring ability - was there to see.
"But he didn't really fulfil his potential at Birmingham - it was difficult because of the way Birmingham played.
"He was a popular player in the changing room, he got a grasp of the Brummie accent quite quickly and he was popular with everyone. It is sad to lose anyone like this."
Benitez's former Birmingham team-mate Craig Gardner, now at Sunderland, tweeted: "Cannot believe Christian Benitez has died.
"I had the pleasure to play with him. He was a top bloke. My thoughts go out to his family."
Benitez scored four goals in 36 appearances during his time in England and came to prominence during the 2006 World Cup in Germany.
The son of Ermen Benitez, one of Ecuador's all-time leading goalscorers, Benitez left Santos Laguna for Club America, another Mexican side, in 2011.