Ramires at the double as Chelsea see off Pompey
The Brazil midfielder's goals, scored in the 85th and 87th minutes, together with an added time fourth for Frank Lampard added gloss to the scoreline after Juan Mata had put Andre Villas-Boas's side ahead in the 48th minute.
That ensured the Blues were spared an embarrassing slip against Championship opponents in a re-run of the two teams' meeting in the 2010 final, which Chelsea won 1-0.
But despite the convincing scoreline, this was another stuttering performance from Villas-Boas's side who are finding their feet after a disastrous run of results in December.
Chelsea failed in their bid to convince Ivory Coast officials to allow Didier Drogba and Salomon Kalou to delay their departure for the Africa Cup of Nations.
That meant Fernando Torres started as the main striker and denied Drogba the chance to stage a repeat of his match-winning goal at Wembley two seasons ago.
Much has changed since that meeting which secured the Premier League and FA Cup double for Carlo Ancelotti's Chelsea team.
Ancelotti left Stamford Bridge just 12 months later while Portsmouth slipped out of the top flight at the end of that season and are currently facing another battle to remain clear of the Championship danger zone.
One thing that hasn't changed, however, is the precarious financial position at Fratton Park and Portsmouth, the 2008 FA Cup winners, came into this tie with uncertainty surrounding the future ownership of the club.
This was certainly a game Chelsea could not afford to take lightly, however, no matter what the status of their opponents.
A disastrous run of recent results was ended only by the narrow victory at Wolves last time out and Villas-Boas's side badly needed a confidence boost.
They had one before kick-off when skipper John Terry was passed fit to start after recovering from a knee problem.
But even with Terry at the heart of Chelsea's defence, Portsmouth created several good chances.
The first of the match fell to the visitors after just two minutes when Dave Kitson collected Marco Futacs's flick and sent a left foot shot narrowly wide.
Pompey right back Aaron Mokoena then went close midway through the half when he headed over from just six yards out from a corner.
And midfielder David Norris also threatened Petr Cechs goal with a snapshot from the edge of the box.
Chelsea dominated possession but created few chances, the best falling to Torres after 13 minutes when the Spain striker produced a full length save from Portsmouth keeper Stephen Henderson with a powerful header.
The hosts raised their game in the second half and three minutes after the break were ahead through Mata.
Ashley Cole contested a loose ball with Kitson, prompting Pompey claims of handball. But referee Anthony Taylor ignored the protests, allowing the Chelsea full back to release Florent Malouda on the left.
Malouda, often criticised by Chelsea fans this season for failing to produce a telling final ball teed up Mata perfectly and the former Valencia man finished it off from close range.
Portsmouth responded well to the blow and could have been level but Chelsea escaped when Cech saved from Futacs and then Norris either side of a goal-line block by Terry from Joel Ward.
Pompey began to tire though, and Chelsea took full advantage in the final minutes with Ramires first nipping in to turn Torres's header in from close range before running from halfway for the third.
And Lampard wrapped up the win with a left footed shot seconds before the final whistle.
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