Portsmouth manager Kenny Jackett has set his players a 90+ points target to give themselves a chance of finishing in the top two.
Promotion rivals Sunderland moved into second in League One with the 1-1 draw against Burton Albion at the Stadium of Light on Tuesday.
There are now only six games to go this season, with five teams still in the hunt for automatic promotion.
Jackett told the Portsmouth News: "We’re on 77 points and we’re going to need 90-plus. We know that there’s not much margin for error, but we’re capable of reaching our aim.
"It is realistic for us to get into the top two and although we don’t need perfection, we need something near it.
"We have to really go for it now – and have a fantastic crowd behind us that we know will back us all the way."
Sunderland, on 80 points, are second in League One with six games to go, with a slender one point advantage over Barnsley in third, though the Black Cats still have a game in hand.
Table-topping Luton Town lead the way, seven points clear of Sunderland, but there are five teams in total realistically battling for the two automatic promotion places.
Sunderland’s fate is in their own hands heading into today’s home game against Coventry City (KO 3pm) but have Barnsley (79), Portsmouth (77) and Charlton (76) breathing down their necks.