First half tries from half-backs Isaac Boss and Ian Madigan laid the foundations for the O2 Ireland Wolfhounds' 14-8 win over England Saxons at Kingsholm, but it was their solidity in defence which was decisive at the end of an exhaustive 80 minutes.
The Saxons hammered away at the Irish defensive line in the closing stages, hunting for the seven-pointer that would have squeezed them home in muddy Gloucester.
But the green defensive wall stood firm under intense pressure, keeping Elliot Daly out right at the death and a final fumble from Freddie Burns near the corner flag confirmed the Wolfhounds as winners.
The game was barely five minutes' old when the visitors attacked from a lineout maul, and scrum half Isaac Boss exposed some poor English defending to touch down to the right of the posts.
His half-back partner Ian Madigan converted before the Saxons responded in the 24th minute thanks to a fortuitous intercept try from winger Anthony Watson.
Burns, who had an off-night with the boot, watched his conversion attempt come back off the post and the Wolfhounds - with captain Rhys Ruddock leading by example as part of an athletic back row - replied within five minutes.
Anthony Foley's men were just that bit sharper in attack and defence and with a strong wind behind them, they made sure to finish the first half in good stead. The three newcomers to this level - Rob Herring, Robin Copeland and Martin Moore - all acquitted themselves well.
Madigan, who was at the heart of Ireland's smartest plays, took a quick tap penalty and spun out of a double tackle to stretch over for try number two which he converted for a 14-5 interval lead.
The second period was rather scrappy at times as Ireland's defence contained what the young English side could throw at time. The nine-point margin remained after Burns hit the woodwork again with a penalty.
Richardt Strauss' welcome return to international rugby was the first of a number of changes made by the Irish management, with the bench emptied by the 70th minute.
Burns split the posts with a 64th minute penalty to bring the Saxons within three points, but the Wolfhounds' greater experience told at crucial stages and they held on for a hard-earned win - a reverse of last January's meeting in Galway which ended 14-10 in England's favour.
The Saxons' starting line-up contained only three full internationals and had an average age of 24. They were quickest out of the traps, launching a kick chase that Fergus McFadden did well to cope with.
A heavy rain shower before kick-off worsened conditions and there was plenty of kicking throughout. Up front, Ireland gradually forced the issue with Copeland, Ruddock and Tommy O'Donnell all impressing in the breakdown exchanges.
The deadlock on the scoreboard was broken following some forward pressure in the English 22. A pinpoint throw from hooker Herring led to a decent maul drive, before Boss dummied past flanker Luke Wallace and Burns' missed tackle allowed the man-of-the-match to scamper over for a seven-pointer.
Full-back Daly threatened for the Saxons soon after, but a tackle from Craig Gilroy and Felix Jones' subsequent turnover saw the Wolfhounds retrieve the situation.
The Irish pack's influence continued to grow with a couple of well-won turnovers and Herring combined well at lineout time with his Ulster team-mates Dan Tuohy and Iain Henderson.
However, Foley's side suffered a setback when they coughed up an unconverted try. Jones' fast-paced pass was fumbled by Gilroy in midfield and the waiting Watson gathered it to sprint in unopposed.
The Ireland Wolfhounds regrouped and hit back through Madigan in the 29th minute. He was hugely influential in the build-up to his try, getting over the gain-line himself and linking well despite the difficult conditions.
The Leinster ace backed himself to score from a close-in penalty, tapping it and shipping a couple of tackles before muscling over the line for a try which television match official Gareth Simmonds confirmed.
The extras were added by Madigan whose kicking out of hand was equally assured, a neat punt downfield keeping Ireland on the move after a heavy, well-timed hit by Robbie Henshaw.
Henshaw and Ulster's Darren Cave were quite the combined force in the centre, continually frustrating the Saxons' attempts to create an opening in midfield.
Amid a slow, set piece-dominated start to the second half, David Kilcoyne was singled out for a scrum infringement but Gloucester clubman Burns hit the left-hand upright with his 30-metre penalty kick.
The Wolfhounds had more defensive duties when facing into the stiff breeze, and Stephen Archer made an immediate impact as part of a turnover-winning choke tackle.
Another of the reserves, Jack McGrath, carried strongly and together with Henshaw he got the Wolfhounds back into scoring range in the hosts' 22.
Their efforts sparked a relentless period of picking and driving on the hour mark and it should have led to a third Irish try, however replacement Simon Zebo was squeezed out by Rob Miller in the right corner.
Burns' successful penalty attempt followed and the Saxons had a tight grip on possession and territory for the remaining 15 minutes.
The Wolfhounds did have an opportunity to build from deep when Strauss controlled a maul out of the 22, and Boss linked cleverly with Zebo to set the winger up for a weaving run into the English half.
But Ireland ultimately had to back their defence to see out the result, aided by a couple of nice touchfinders from replacement Ian Keatley who joined Madigan in a rejigged back-line.
The Saxons had a stranglehold on the ball late on, working some space for the dangerous Daly on the left wing where McFadden was equal to the challenge.
Further Saxons pressure was absorbed with Jordi Murphy, another Irish debutant at this level, getting over a ruck ball to force a relieving penalty in the 22.
A powerful shunt in the scrum should have helped the Wolfhounds claw back more territory, but the Saxons retained possession and mounted one final surge from which Daly and Burns both went close.
The result ended the Wolfhounds' two match-losing streak against the Saxons, and gave watching Ireland head coach Joe Schmidt plenty of food for thought ahead of the start of the RBS 6 Nations next week.
TIME LINE: 5 minutes - O2 Ireland Wolfhounds try: Isaac Boss - 0-5; conversion: Ian Madigan - 0-7; 24 mins - England Saxons try: Anthony Watson - 5-7; conversion: missed by Freddie Burns - 5-7; 29 mins - O2 Ireland Wolfhounds try: Ian Madigan - 5-12; conversion: Ian Madigan - 5-14;Half-time - England Saxons 5 O2 Ireland Wolfhounds 14; 49 mins - England Saxons penalty: missed by Freddie Burns - 5-14; 64 mins - England Saxons penalty: Freddie Burns - 8-14; Full-time - England Saxons 8 O2 Ireland Wolfhounds 14
ENGLAND SAXONS: Elliot Daly (London Wasps); Anthony Watson (Bath), Matt Hopper (Harlequins), Sam Hill (Exeter Chiefs), Charlie Sharples (Gloucester); Freddie Burns (Gloucester), Joe Simpson (London Wasps); Alex Waller (Northampton Saints), Jamie George (Saracens), Tom Mercey (Northampton Saints), Charlie Matthews (Harlequins), George Kruis (Saracens), Calum Clark (Northampton Saints) (capt), Luke Wallace (Harlequins), Dave Ewers (Exeter Chiefs).
Replacements used: Henry Slade (Exeter Chiefs) for Hill (31 mins), Rob Miller (Sale Sharks) for Hopper, Scott Wilson (Newcastle Falcons) for Mercey (both half-time), Elliott Stooke (Gloucester) for Matthews, Sam Dickinson (Northampton Saints) for Ewers (both 50), Nathan Catt (Bath) for Waller (60), Dave Ward (Harlequins) for George (64), Dave Lewis (Exeter Chiefs) for Simpson (74).
O2 IRELAND WOLFHOUNDS: Felix Jones (Shannon/Munster); Fergus McFadden (Old Belvedere/Leinster), Robbie Henshaw (Buccaneers/Connacht), Darren Cave (Belfast Harlequins/Ulster), Craig Gilroy (Dungannon/Ulster); Ian Madigan (Blackrock College/Leinster), Isaac Boss (Terenure College/Leinster); David Kilcoyne (UL Bohemians/Munster), Rob Herring (Ballynahinch/Ulster), Martin Moore (Lansdowne/Leinster), Iain Henderson (Ballynahinch/Ulster), Dan Tuohy (Ballymena/Ulster), Rhys Ruddock (St. Mary's College/Leinster) (capt), Tommy O'Donnell (UL Bohemians/Munster), Robin Copeland (Cardiff Blues).
Replacements used: Richardt Strauss (Old Wesley/Leinster) for Herring (half-time), Stephen Archer (Cork Constitution/Munster) for Moore, Jack McGrath (St. Mary's College/Leinster) for Kilcoyne, Simon Zebo (Cork Constitution/Munster) for Gilroy (all 50 mins), Jordi Murphy (Lansdowne/Leinster) for O'Donnell, Ian Keatley (Young Munster/Munster) for Henshaw (both 60), Robbie Diack (Malone/Ulster) for Henderson, Kieran Marmion (Corinthians/Connacht) for Boss (both 70).
Referee: Ian Davies (Wales)