Prior to the Games, the 22-year-old set himself an ambitious target of winning seven medals from his seven events and got off to a positive start yesterday with silver in the 400m freestyle.
Guy had been in line for another podium finish during tonight's 200m freestyle final, coming from second at the halfway mark to be in the lead come the final 50m. However, he was unable to keep the momentum going to the end, allowing three of his competitors to edge ahead.
South Africa's Chad le Clos was considered one of the main contenders to increase his medal tally, having won gold in the men's 50m butterfly just 19 minutes earlier, but could only manage seventh on the night with a time of 1:47.46.
Guy has another chance at medalling later tonight when he competes as part of the 4x100m freestyle relay.