Rotterdam, The Netherlands (SportsNetwork.com) - Seventh seed Mikhail Youzhny suffered an opening-round upset Tuesday at the $1.85 million ABN AMRO World Tennis Tournament.

Dutch crowd favorite and wild card Igor Sijsling easily took out the Russian Youzhny, the 2007 champion and 2007 runner-up, 6-2, 6-2, on the indoor hardcourts at Ahoy Rotterdam.

Also on Day 2, Latvian Ernests Gulbis topped Uzbekistan's Denis Istomin 6-4, 7-6 (7-4) and last week's Zagreb titlist Marin Cilic of Croatia leveled Czech Lukas Rosol 6-2, 6-2. Up next for the in-form Cilic will be fifth-seeded 2011 Rotterdam finalist Jo-Wilfried Tsonga.

This week's top seeds are reigning Rotterdam champion and former U.S. Open winner Juan Martin del Potro and reigning Wimbledon titlist and 2009 Rotterdam champ Andy Murray. Del Potro will open his week against last week's Montpellier champ Gael Monfils, while Murray will encounter France's Edouard Roger-Vasselin in the round of 32 on Wednesday.

Del Potro defeated Frenchman Julien Benneteau in last year's Rotterdam finale and was the runner-up here in 2012.