This end of the season rightly resembles the board game Diplomacy, a mixture of alliances and broken half-promises to friends, treachery to treasure. So, a few hours after Tottenham Hotspur had closed the Premiership door on Liverpool, helping out their old friends Arsenal, United were slamming it shut at the other end for Ipswich Town, who obviously have a season ticket on football's rollercoaster.
Ipswich, who tried hard but not hard enough, now have to beat Liverpool at Anfield and hope Sunderland lose to Derby County at home.
If Sir Alex Ferguson had his mind on Tuesday's Champions League semi-final second leg against Bayer Leverkusen, it did not show. As he promised, he gave this match every respect, hoping of course for a late cock-up by Arsenal at Bolton Wanderers tomorrow.
Any team bolstered by the inclusion of Roy Keane could never be accused of being understrength, but neither were United let down by John O'Shea, the young Irish centre-back who has turned in a couple of impressive performances this season, or by Diego Forlan, Michael Stewart and Luke Chadwick.
All in all, United looked considerably more at ease with themselves than they did on Wednesday evening against Bayer Leverkusen. Keane moved freely and does not seem inconvenienced by the injury that threatened to ruin his season only three weeks ago, and Wes Brown had a more convincing match alongside O'Shea.
Behind them, Roy Carroll was alert to a couple of early threats that might have proved embarrassing had Ipswich made more of them. Martijn Reuser found himself unmarked but off-balance and his header nestled in the goalkeeper's arms after the first proper chance of the match. Moments later, Sixto Peralta found himself three yards out with the ball at his feet, only to get tangled up in O'Shea's challenge.
At the other end, Van Nistelrooy pulled off perhaps the miss of the season. Just before the half-hour, Forlan's free-kick into the box found Keane, who tapped it down to Brown, facing the wrong way. The defender back-heeled it into the Dutchman's path and the Premiership's most lethal striker hit the ball over Andy Marshall and the crossbar, from barely two yards out.
As on Wednesday, he made amends from the spot, although it looked a dubious penalty. In the final minute of a half in which the honours had gone only marginally United's way, he ran into space to drag down Keane's precise lob, found John McGreal and Titus Bramble in close attendance and down he went. It was not convincing, although his strike into the bottom left corner was.
Paul Scholes replaced Stewart at the start of the second half as Ferguson sought to make the points safe; if the maths do fall his way, he will not want to look back and say he blew it against Ipswich on their way down.
There were a couple of close calls early in the half, though, as Bent went close with a header and Matt Holland stroked a firm volley straight at Carroll from 30 yards.
On the hour, Dennis Irwin got in front of Reuser at the far post with the goal begging and the ball almost squirted into the net from the corner. United, so relaxed going forward, were vulnerable when turned by the occasional burst by Bent and Reuser.
In the middle, Keane controlled the pace and direction of play as if everyone else were on pieces of string. He has the gift that only a few of his kind possess to create an invisible shield around himself.
Ipswich lacked urgency in what was clearly a crisis. And, when young Darren Bent came on for his second senior game, he mysteriously replaced Reuser, their free-kick specialist.
In the absence of David Beckham, United handed those duties to Irwin, who tested Marshall with a dipping effort from 35 yards.
Mikael Silvestre replaced Chadwick to shore up the defence, but Tommy Miller nearly spoilt the story with a shot on the turn that went only inches past a post. Now it was Ipswich who looked vibrant and threatening; United had to compose themselves. After looking good earlier, at the end they were doing what they are unaccustomed to doing: hanging on.
