Great Britain's Heather Watson has exited the Miami Masters at the round one stage.

It appeared that the 20-year-old was bound for a routine victory earlier today when she claimed the first set against Japan's Ayumi Morita 6-1.

Then in the second set, Watson opened up a 4-1 advantage, which left her requiring just two more games to book her slot in the next round.

However, Morita responded by claiming the set 7-5 to force a decider, before going on to win that 6-4.

The defeat means that Watson has now lost in the opening round of the last two Masters 1000 tournaments.