Guardiola, who won the Champions League as a Barca player in 1992, has led the Catalan giants all the way to the last four in his first season as coach.
Barcelona are also top of the Primera Division and face Athletic Bilbao in the final of the Copa del Rey next month.
A possible treble is therefore still on for the Catalans but the Champions League is likely to be the hardest to win of those three competitions and Guardiola hopes his players can avoid getting dragged into a physical battle against Chelsea.
"They are a very strong team physically and have a lot of experience," he said.
"From a physical point of view, they are much more powerful than us, so my players will have to dominate."
Guardiola is particularly concerned by the threat Guus Hiddink's side pose from set-pieces.
"People like (Branislav) Ivanovic, (John) Terry, (Michael) Ballack and (Didier) Drogba are strong in the air, so the less free-kicks and corners we give away the better - because they are better than us in that respect," he said.
After Tuesday night's first leg, the two sides meet again in London on May 6, and Guardiola believes the second match will decide which team progresses to the final in Rome later next month.
"It will be decided in London and we won't be relaxed, whatever the result on Tuesday," he said.
Guardiola was part of the Barcelona side that overcame a 3-1 defeat at Stamford Bridge with a stunning 5-1 win at the Nou Camp in 2000.
That success - which saw the Catalans advance to the semi-finals, where they were then beaten by Valencia - was inspired by Luis Figo.
"We played well that night and Figo was immense," Guardiola said. "But we have players like him who can inspire us this time."
Barcelona also knocked out Chelsea on the way to the title in 2006, having been eliminated by Jose Mourinho's side the previous season following a 4-2 defeat in London.
Nevertheless, Guardiola insists Barcelona will remain true to their attacking philosophy in the two games against Hiddink's side.
"We will play our attacking game - that's the only way we know how," he said.
Xavi also claimed the Catalans will set out to attack.
"If we play like we can and we maintain our attacking philosophy, they will suffer. We'll look to imprint our rhythm and intensity on the game from the very first minute," he said.
Nevertheless, Xavi believes Chelsea will be difficult to beat.
"They are complicated team to play against - they have a lot of individual talent and they're physically strong," he said.
Guardiola, meanwhile, admits he is living out a dream as coach of Barca.
He started out as a ball-boy at the club, before progressing through the youth system to become a key component in Johan Cruyff's legendary 'Dream Team'.
Guardiola starred as Barcelona won a string of titles - many as team captain - under Johan Cruyff, Bobby Robson and Louis Van Gaal.
And now, in his first season as coach, Guardiola is excited by his side's Champions league adventure.
"I'm like a little boy with new shoes," he said.
"I'm immensely happy, I'm living a dream and I don't know when it will be repeated so I want to enjoy it to the maximum."