Chelsea have forged a five-point lead at the top of the Barclays Premier League, and Terry senses that opponents are beginning to fear the Blues once again, as they did during Jose Mourinho's time.
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Like Mourinho's Chelsea, Ancelotti's team are proving superb at Stamford Bridge. They have not conceded a goal there since the first day of the season, but their destiny lies on the road according to the centre half who will captain the club for the 300th time tonight.
'I really think we're getting back that invincible feeling we had three years ago,' said Terry. 'I listen to the other players when we're away with England and they're all talkingabout how well we're playing. They're fearing us again.
VIDEO: Terry on Porto test.
'We're playing well and could go on to great things again this year. We had that when we were winning the Premier League and we're getting close to that again. It's key to get that back.
'We know what it takes to win major titles and we need to produce that now. It takes winning runs. It takes periods when you keep on top, striding from result to result.
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'Good performances, strong performances, dogged performances and everyone in the squad playing their part.
'We're top of the Premier League and top of our Champions League group. Now is the time we can pull away. It's four away games in a row and that's the challenge major title winning teams rise to.
'This can be another special year in the history of Chelsea. The next few weeks can move us towards our goal.'
Victory in Porto will confirm Chelsea as Group D winners with a game to spare and secure a top seeding in the competition's first knock-out round.
They return for a derby at Arsenal on Sunday, a Carling Cup quarter-final in Blackburn and a Premier League showdown with Manchester City, a week on Saturday.
'Manchester City and Arsenal are serious top four contenders,' said Terry. 'There's also Blackburn away in the Carling Cup. Victory and we're through to the semi-finals.
'On the two occasions we've won the Carling Cup recently we've gone on to win other things - the Premier League in 2005 and the FA Cup in 2007. It's the appetiser.
'The Premier League is throwing up all sorts of difficult away games. We went to Wigan and lost, away to Villa and lost as well. It's about regrouping, keeping everyone fit and believing in what we can do.'
Chelsea's captain also applauded the manager's policy of rotating his squad. With Arsenal in mind, Ancelotti will start with Didier Drogba and Michael Essien on the bench in Portugal and Yuri Zhirkov will start only his second game since his £18million summer transfer in order to give Ashley Cole a breather.
Ricardo Carvalho and Deco, two of five former Porto players in Chelsea's squad, return in the Estadio do Dragao after sitting out Saturday's 4-0 win against Wolves, as does Branislav Ivanovic.
Ancelotti said: 'We want to win the group and show our personality and courage. That is a difficult thing to do in this stadium.'
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This time last year, Chelsea were top of the Premier League on goal difference from Liverpool and eight points clear of Manchester United, who had a game in hand.
But a Champions League draw in Bordeaux was followed by defeat at home to Arsenal and they won only four of the next 10 before Luiz Felipe Scolari was sacked in February.
Scolari's painful lesson will guide Ancelotti, especially as Guus Hiddink is already making noises about a possible return to club football after Russia's failure to reach the World Cup final.
'We've had a good start but we're not getting carried away,' said Terry. 'We started well last year and then threw it away.'
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