Sjeng Schalken (Dutch pronunciation: [ɕɛŋ ˈsxɑlkə(n)]; born 8 September 1976) is a coach and a former professional tennis player from the Netherlands.

Schalken won his fourth title against Tommy Haas in Auckland in January 1999, exactly three years after his younger brother died of cancer, and dedicated the victory to him.

Schalken moved through to the second week beating Ivan Ljubičić and Sargis Sargsian, where on the Arthur Ashe Stadium, he bested former world No.

Nevertheless, he once more excelled on grass, defending his 's-Hertogenbosch title with a repeat win over Frenchman Arnaud Clément in the final, before matching the previous year's quarterfinal at Wimbledon.

Schalken won just one match in a series of indoor tournaments that October, but other things were on his mind; he married his fiancée Ricky Pfennings on 21 November.

But his form then took a sharp downturn and he managed only one quarterfinal in the next five months, a period that reached its lowest point when he was defaulted from his match with Guillermo Cañas at the Masters Series event in Miami for verbally abusing the umpire.

[5] There were other dramatic moments too; the weekend before the Rome Masters tournament, a fire broke out in the hotel where many players were staying including Schalken and his wife.

His 2005 season proved as limited as the second half of 2004 had been, his most notable results being two five-set victories against Swiss players Marco Chiudinelli and Stanislas Wawrinka in the Netherlands' Davis Cup win over Switzerland.

He injured his right Achilles tendon in the spring and was forced off the tour in July, since then his only tournament at any level to date has been a semifinal showing in the Bergamo Challenger in Italy in February 2006.