But the Aussie winger acknowledged only a maximum return from the final two games will do if a top-six place is to be achieved.
The Pompey dressing room was left floored as John Marquis late, late own goal denied their victory at Accrington Stanley.
But Charlton conceding in stoppage time against Crewe Alexandra changed the complexion of the top-six race, as they were held to a 2-2 draw.
It means two wins from Pompey will allow them to overhaul Nigel Adkins’ side, if they falter in any of their three remaining fixtures.
And with a trip to Accrington before clashes with high-flying pair Lincoln City and leaders Hull to come, Williams knows that will not be an easy task.
He added: ‘It’s six points or nothing for us - then we just have to wait and see.
‘Hopefully results can go our way because Charlton have got quite a hard run-in.
‘It’s two points ahead of them with the game in hand.
‘Oxford have got two games left and we’re a point in front of them.
‘Everyone was emotional after the game because we were 20 seconds away, but we’ve still got the belief.
‘We just have to go hell for leather in these final two games and then hope the football gods are with us and we can get into the play-offs.’
Williams highlighted how Pompey are certainly not going to die wondering in the bid to reach the top six, with Cowley employing an attacking line-up featuring wing-backs in recent games.
It means as the Blues go forward there’s an forward quintet, with the wing-backs aided by two attacking players in the channels and striker John Marquis against Bristol Rovers on Saturday.
At Accrington, Cowley tweaked the formation so Marquis was joined by Ronan Curtis in attack with George Byers in the number 10 role.
Williams added: ‘When we get into our stride pattern it’s an attacking five.
‘We basically end up with two wingers, two 10s and a striker.
‘That’s how we want to play it, with the two midfielders then popping the ball around and the centre-halves stepping in a little bit.
‘Wimbledon’s pitch looks pretty nice so we need to go out there all guns blazing. It’s do or die now. If we win the next two games I think we can do it.’
A message from the Editor, Mark Waldron
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