Pompey's were left hanging on to top spot in League One after a disappointing afternoon at Fratton Park.
They were beaten 3-0 by Leyton Orient after producing a performance that fell below their previous high standards.
Shaq Forde, Jordan Brown and Dan Agyei all netted before the break for the visitors, while John Mousinho's men also saw a Colby Bishop penalty saved.
Fans can watch the key moments (top video) or register with iFollow to view extended highlights and a full match replay.
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