Jan Poortvliet made the two changes to the starting line-up. Fit-again Lee Holmes returned to the side, with Bradley Wright-Phillips dropping to the bench, and Alex Pearce coming in for the injured Morgan Schneiderlin.
Lancashire and Gillet replaced Robertson and Wotton on the bench.
First half - crusing, then bruising
Saints started the first half in good form and were absolutely cruising against a very nervous looking Forest defence who conceded cheap possession all too often, but as ever Saints failed to punish them.
Things might have been different had Drew Surman's sweet strike not hit the outside of the post, but it may only have delayed the inevitable as Forest starting hitting their stride.
Davis has made some great saves this season, but his fingertip save from a shot just yards out may have been the best of the lot. Saints failed to heed the warning as Forest slowly regained confidence and started to hit Saints on the counter.
Despite having less of the ball they had the better chances and it was no real surprise to see Morgan power in a free header from an albeit debatable freekick. It was more set piece ineptitude, with Morgan one of three Forest players completely unmarked.
Second half - from bad to worse
The goal seemed to knock what fight was left out of Saints as the pressure of a solitary home win all season and a vital six pointer took its toll.
Saints were second to nearly every ball as their passing game fell apart under Forest's pressing. It was only Forest's inability to take their chances, a failing they share with Saints, that kept the game up for grabs.
Saints have shown some memorable, if often fruitless, comebacks this season, but it just never came. Garner's wonder chip from nearly 40 yards did at least add some interest to the dire proceedings as Saints began to panic under the pressure and got progressively worse.
Saints did try and get the ball and men into the box, but without any real movement or desire to win the ball, coupled with some very poor delivery, it all proved pointless.
On the Cross verdict
Forest manager Colin Calderwood somewhat ungraciously described this as not in their top 10 performances this season, but this was definitely in Saints' worst 10, perhaps even the Christmas Number One!
So much of football is played in the head. At the start of the game Saints were cruising, Forest were unable to get hold of the ball and looked an accident waiting to happen in defence, but within the space of 20 minutes the same set of 22 players reversed roles.
On paper these were two very similar sides. Both fallen Premiership veterans, trying to rebuild with a squad of very young players keen to take their chance. The difference is that Forest are on the up and Saints seem yet to have hit rock bottom. The difference in desire and organisation was an embarrassment as the heads went down in the second half.
You expect inconsistency from the youngsters, but you also expect them to improve as the season progresses. The real concern is that the team is getting worse not better.
Poortvliet looks a man running out of ideas and hugely frustrated that his young side cannot transfer the training ground slick football onto the pitch when the pressure of match day comes along. He's tried reshuffling players, he even tried 4-4-2 in the last 30 minutes, but it's just not working.
Saints are now just a point off the bottom three and have a tough run of fixtures coming up and it is difficult to see us avoiding the relegation zone in the next few weeks. Then of course is the transfer window and the inevitable player departures as this squad risks getting stripped of what genuine quality it has.
Something has to change and change fast or we will be emulating Forest's humiliating relegation to League One.