Laura Robson has admitted that she was hugely disappointed by her first-round exit at the US Open.
The 21-year-old crashed out of the competition as she was beaten in three sets by Elina Vesnina, despite taking the first set 6-3.
Robson has conceded that she was frustrated by her defeat because she believes that she should have secured the victory.
"Any loss is tough, but that one especially because if we're being honest, I should have won," Robson told BBC Sport.
"That definitely makes it harder and makes me more determined to work harder for the next one."
Robson's last victory in a Grand Slam came in 2013 at Flushing Meadows.
