In a match at the RDS in Dublin, watched by 16,800 and against an Algeria side which was captained by former Sky Blue Yazid Mansouri and one that will face England in Cape Town in the World Cup on June 18th. Westwood got his first touch of the ball just before the four minute mark when he kicked upfield.
The first thirty minutes saw a routine kick and two catches for the City number one in what was a tight match before full debtant Paul Green got his head very low from a free kick to nod Ireland in to a 31st minute lead.
Ireland added a second, six minutes into the second half when Duff's cross from the left was flapped by the keeper and Robbie Keane volleyed the loose ball into the net from twelve yards.
The Spurs striker, who had been on loan at Celtic, hit the post in the 63rd minute before Yazid Mansouri, who was booked for kicking out was replaced in a triple change in the 66th minute.
An easy save for Westwood came in the 70th minute as Ireland controlled the proceedings.
In the 83rd minute, Guadiola hit the bar with a header, Ireland broke up the other end and Keane was pulled down. He got up to take the spot kick and slotted the ball into the corner of the net to put Ireland 3-0 up and the match out of sight.
Keiren Westwood was replaced after 85 minutes and 31 seconds by Scunthorpe's Joe Murphy who won his second cap as Ireland recorded their best victory under Giovanni Trapattoni.
Ireland's next game is in 75 days time against Argentina at the new Aviva Stadium that has been built on the site of Lansdowne Road.