Southampton travel to Portman Road just days after their 1-1 draw with Middlesbrough on Friday meant they failed to take full advantage of Leicester and Leeds dropping points.
Ipswich were narrow 1-0 winners when the two sides faced each other at St Mary’s earlier this season, a result Armstrong said hurt the squad.
Russell Martin’s side could cut the gap between them and the Tractor Boys to seven points with a win while still having two games in hand.
“We know where they are in the table and how well they have done this year,” Armstrong told the Daily Echo.
“They are top of the table, having come up from League One last season, that’s an incredible achievement.
“We have got to go there and be ourselves and put things right. That defeat to them earlier this season hurt, they all did.
“When you lose four on the bounce they all hurt the same amount as each other. We have to make sure we put the work in ahead of going there to put on a shift.”
The trip to Ipswich marks the first of eight games for Southampton in April, a run in which squad depth and staying focused will be crucial.
Boro’s equaliser on Friday came in the 90th minute – a point of frustration for supporters, players and coaches alike.
The south coast side can ill afford any more moments like that if they are to sneak into the final automatic promotion spot.
“If we are not putting them away then we need to be solid at the back,” Armstrong concluded. “This is a league where you get punished if you switch off for a minute. It’s the same in the Premier League.
“It’s something that we really need to make sure we are better at. We have the depth. Everyone is taking off each other. We need to keep that up because there are a lot of games in such a tight space of time.”
