Swansea City are in round five of the FA Cup after dumping holders Portsmouth out of the competition at their own ground.
It finished 2-0 with both goals coming in the first-half courtesy of Nathan Dyer and a Jason Scotland penalty.
Despite having further chances in the second period Roberto's side had to endure many nervy moments as Pompey looked to get back into this tie, including a Peter Crouch header that hit the post.
But the visiting side, backed by over 3,000 passionate fans, held on to record a famous victory.
The Swans made two changes to the starting eleven for this fourth round FA Cup tie against Portsmouth at Fratton Park.
The first change came between the sticks where Dimi Konstantopoulos replaced Dorus de Vries to play in his first game since extending his loan from Coventry.
Swansea's defence remained unchanged with the only other change coming in midfield where Leon Britton, returning from suspension, came in for Mark Gower.
That meant that the pint-sized former West Ham player slotted straight into the middle of the park with Jordi Gomez moving back out wide.
Pompey: David James, Martin Cranie, Sol Campbell (C), Sylvain Distin, Nadir Belhadj; Sean Davis, Richard Hughes (Younes Kaboul, 84'), David Nugent (Kanu, 46'), Jermaine Pennant, Armand Traore (Hermann Hreidarsson, 46'); Peter Crouch.
Not Used: Asmir Begovic, Noe Pamarot, Arnold Mvuemba, John Utaka.
Swans: Dimi Konstantopoulos; Angel Rangel, Garry Monk (C), Ashley Williams, Alan Tate; Joe Allen (Gorka Pintado, 61'), Leon Britton, Darren Pratley, Jordi Gomez, Nathan Dyer (Mark Gower, 79'), Jason Scotland.
Subs: Dorus de Vries, Andrea Orlandi, Owain Tudur Jones, Guillem Bauza, Albert Serran.
Attendance: 17, 357 Away: 3,144
Referee: Andre Marriner (West Midlands)
The visiting side started this clash in fine form and, with the backing of over 3,000 Swans fans in full voice, were on the attack from the off and within the opening three minutes had already won two free-kicks in opposition territory.
Pompey took another minute or two to create their first opening as Sean Davis fired low at goal but the threat was dealt with by Ashley Williams.
Winger Nathan Dyer, making only his second start in Swansea colours, was getting some stick every time he was on the ball but was causing stand-in full-back Martin Cranie some problems with his pace down the left.
The Swans had the first clear-cut effort of the afternoon on nine minutes as Angel Rangel fired across goal and just past the post. He received Jordi Gomez's quick free-kick and, after a neat one-two with Darren Pratley, found space on the edge of the box before pulling the trigger.
Gomez had a chance of his own two minutes later as he fired first time at David James following fine work by the pacy Dyer down the wing. The on loan Southampton youngster was having a fine start to this contest and even forced a save out of James on 20 minutes from distance, but didn't trouble the England international.
The Swans were on top of this fixture from the word go and all of their hard work delivered a goal on 26 minutes courtesy of Nathan Dyer, which pleased the home crowd!
Leon Britton picked out Jason Scotland on the left-hand touchline, the striker then chipped over the top of Sol Campbell for Dyer to race onto the end of his pass before unleashing a low drive into the bottom corner.
Jason Scotland almost found an opening moments later, only to be denied by a last ditch Sol Campbell tackle, while Dimi Konstantopoulos made a fantastic stop from Peter Crouch's effort on the half-hour.
Dyer continued to frustrate the home defence with his pace while Pompey continued to seek a way back into this tie. The closest they came was when Peter Crouch fired a half volley well over the top of goal on the stroke of half-time.
The Swans were given an opportunity to extend their lead in stoppage time when Jordi Gomez was brought down inside the area by Belhadj. Andre Marriner awarded a penalty with Scotland, who started the initial move, placing the ball on the spot and firing low past James into the corner.
Half-Time: Pompey 0 Swans 2
Portsmouth made two changes at the break with Hermann Hreidarsson and Kanu taking to the field, and the opening five minutes were a bit nervy for the visitors as Pompey pressed for a goal.
They almost had it on 53 minutes as Crouch met Pennant's cross with his head, only to be denied by another fine Konstantopoulos stop.
Nathan Dyer almost had a chance to kill off the tie three minutes later, but he shot straight at James from eight-yards, while a Jordi Gomez free-kick was parried by the 'keeper and deflected wide for a corner moments afterwards.
Pompey went straight down the other end but were denied by another excellent Konstantopoulos save, this time from Sean Davis, but a moment of madness from the Greek almost let in substitute Kanu but, fortunately, the Swans' lines were cleared.
Roberto made his first change of the afternoon just after the hour when Joe Allen was replaced by Gorka Pintado.
El Toro had a sniff at goal with 68 minutes on the clock only for David James to reach the ball first, but the 'keeper's clearance went straight to the feet of Jason Scotland who, with a first time shot, sent it straight back at the 'keeper.
Pompey continued to press and had another excellent opportunity to get back into this game on 73 minutes when Pennant's corner was headed onto the post by the towering Crouch.
It should have been game over with a little over 10 minutes remaining as an instinctive break by the Swans down the left saw Dyer play the ball across the face of goal to Gomez, he took a touch and saw his strike deflect off James' body and drift wide for a corner. Jason Scotland also had a chance on 80 minutes that beat James from distance but flew just wide.
But Pompey continued to pressure and as time was running out for Tony Adams'side they were denied yet again by Konstantopoulos as Kanu played through Pennant, Dimi made himself look big to stop the Liverpool loanee from close-range.
Despite some nervy moments in the closing stages the Swans held on to record a famous victory against the holders.
