The visitors showed their attacking intent from the outset at St. James' Park, twice testing the reflexes of Nick Pope during a high-octane start to proceedings.
Reluctant to simply soak up the pressure, Newcastle clapped back with a period of sustained pressure.
Anthony Gordon’s energy down the left flank was causing Lyanco all sorts of problems, and the wide man was agonisingly denied by the post when he slid a low effort past the onrushing Alex McCarthy.
The hosts remained in the ascendancy for the majority of the half, but crucially, Southampton made the all-important breakthrough as HT approached.
An incisive breakaway cut through the Magpies' defence and was rounded off by Stuart Armstrong’s first-time finish, injecting the Premier League’s bottom club with renewed hope.
Spoilt for choice in terms of in-form goalscorers, Eddie Howe brought on Callum Wilson at HT, and the Newcastle no.9 duly repaid his manager’s faith by netting the equaliser 10 minutes later.
The south coast side had withstood waves of attacks in the first half, but their defence finally buckled when Alexander Isak picked out Wilson, who blasted a shot beyond the helpless McCarthy from close range.
The Magpies were relentless in their pursuit of a second goal, continually knocking at the Southampton door and they inevitably took the lead to shatter Southampton’s hopes.
After VAR had denied Wilson for an offside in the build-up, Sven Botman sent a header into the unfortunate Theo Walcott to finally hand the Magpies the lead.
Still with their foot on the gas, Newcastle then put the game to bed when Wilson kept his composure to round McCarthy and tuck in a third goal nine minutes from time.
Southampton were left shellshocked by the home side’s onslaught and had no response as time ticked away.
The result leaves the Saints without a win in nine, languishing at the foot of the PL table six points from safety.
As for Newcastle, a return to the UCL for the first time since 2002/03 looks all but guaranteed thanks to their commanding lead over the chasing pack.
Flashscore Man of the Match: Callum Wilson (Newcastle United)
