The first match finished all square at Fratton Park on Friday night.
Pompey took the lead in the 37 minutes with a strike from Marcus Harness before Oxford United equalised during injury time at the end of the first half.
The teams were unable to be separated after 90 minutes and Extra Time.
Pompey fell to defeat in the penalty shoot out losing 5-4.
See all the best photos from the first half action.
1. Oxford vs Portsmouth
Pompey take on Oxford in the second leg of the League One play-offs. Photo: Robin Jones
2. Oxford vs Portsmouth
Pompey fans find a vantage point to watch at the Kassam Stadium Photo: Robin Jones
3. Oxford vs Portsmouth
Pompey's Ronan Curtis breaks free of Mark Sykes of Oxford United Photo: Robin Jones
4. Oxford vs Portsmouth
Ronan Curtis breaks free of Mark Sykes of Oxford United Photo: Robin Jones
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