Cameron Norrie progressed through to the St Petersburg Open second round after beating American Taylor Fritz in three sets.
Norrie battled hard to overcome the American 6-4 4-6 6-3, with the Briton emerging victorious despite Fritz being ranked 47 places higher in the rankings.
British number one Dan Evans had three matches points to get the better of Stan Wawrinka and join Norrie in the last 16, but he could not see the win through.
Wawrinka battled back to take the second set before progressing with a 3-6 7-6 (3) 7-5 success.
Norrie will play either Mikhail Kukushkin of Kazakhstan or Serbia's Miomir Kecmanovic in the last 16.
Elsewhere, Stefanos Tsitsipas withdrew from the tournament because of a "minor" leg injury picked up at the French Open.