Keith Earls tied Ireland's World Cup try-scoring record with a brace in 44-10 victory over Romania to take Joe Schmidt's men top of Pool D, before suffering a concussion scare.
Munster flyer Earls took his World Cup try tally to seven in Ireland's routine six-try win, drawing level with Brian O'Driscoll to top Ireland's tournament record.
Earls underwent a pitchside Head Injury Assessment (HIA) midway through the third quarter and though he returned to action, he was replaced permanently 10 minutes later.
Tommy Bowe claimed a try brace of his own in a strong showing, with Rob Kearney claiming a fifth but suffering what looked a minor hip injury in the process.
Chris Henry drove home the sixth score, cementing top spot in the pool with two wins from two matches.
Three months ago the injury-dogged Earls was a huge doubt even to make this World Cup, but the 27-year-old has since ended his 29-month Test absence and become an integral part of Ireland's campaign.
Bowe shook off the memory of his nightmare showing in the final warm-up match against England at Twickenham on September 5.
The Ulster flyer was desperate to prove his World Cup point after being dropped for Ireland's 50-7 opening victory over Canada.
The 31-year-old was at fault for Jonny May's try in Ireland's 21-13 defeat to England at the start of the month, but returned to form against Romania.
Bowe will now hope to challenge the newly-established first-choice wings of Earls and Dave Kearney for the pivotal Italy and France clashes.
The process of forcing his way back into the starting XV is complicated by Earls' strong form however, with Dave Kearney also impressing across the warm-up battles and against Canada.
Ireland's relentless support broke another World Cup record, the 89,267 crowd a new all-time high competition attendance.
New Zealand's clash with Argentina set an 89,019 record on the tournament's opening weekend, and Wembley came up trumps once more on the stats front.
Madigan and Valentin Calafeteanu traded penalties at the top of the clash, before Simon Zebo thought he had sparked the rout.
The Munster flyer dribbled down the left wing to round Adrian Apostol, scooping up before sneaking into the corner.
Zebo's jubilant celebrations were cut short however, as a review showed his was just in touch when he reclaimed the ball and the try chalked off.
After Madigan slotted his second penalty Ireland broke the try deadlock thanks to Bowe's inch-perfect finish.
Earls claimed Eoin Reddan's box kick, Chris Henry and Jamie Heaslip raced on, and then quick hands down the line afforded Bowe just enough space to slide home.
Earls then raced into the left corner to double the try-count, Zebo exploiting Apostol wandering off his wing with a floated scoring pass to the Munster speed man.
Ireland turned around 18-3 to the good, comfortable and in control, but doubtless frustrated at several missed opportunities.
Schmidt's side punted two eminently-kickable penalties to touch in the half, keen to claim the four-try bonus point as soon as possible.
Though both those forays came to nought Ireland still eased to the try bonus after the turnaround.
Earls grabbed his second try thanks to a savvy grubber from Reddan, after a driving lineout edged Ireland within spitting distance of Romania's line.
After Earls had successfully passed his pitchside concussion evaluation, replacement Paddy Jackson was taken out in mid-air by Florin Ionita.
Referee Craig Joubert and Television Match Official (TMO) Shaun Veldsman ruled the infringement only worth a penalty, when in truth Ionita should have received a yellow card.
Csaba Gal was sin-binned moments later however, for killing the ball on his own tryline. From the scrum Bowe slid home for the bonus-point score, Reddan's runaround exploiting the extra man.
Rob Kearney claimed the fifth score straight from the restart, Zebo sending the replacement wing home.
The seasoned full-back, operating on the wing, picked up a knock in the process though, and was replaced shortly afterwards.
Ovidiu Tonita capped a driving maul for Romania's sole and consolation try next, with Florin Vlaicu converting.