Terry was expected to miss England's first friendly of the season with knee ligament damage.
However, as McClaren was coming to terms with the loss of Wayne Rooney from next month's crucial European Championship double-header with Israel and Russia, McClaren received the news that Terry was back in full training and expected to feature at Anfield this weekend.
And, while the defender is unlikely to reach peak fitness within seven days, McClaren intends to play his skipper against the three-time world champions.
"If he is playing for Chelsea on Sunday, I want to include him in my squad," confirmed McClaren.
"He is our captain and our leader. He is the epitome of what we want to be as a team."
Terry will be joined by Owen Hargreaves, Michael Owen and, in all probability, David Beckham when England report for duty in Watford on Monday.
Although the quartet's actual involvement may be limited, McClaren is aware how crucial their collective presence will be when the bid to reach the finals in Austria and Switzerland resumes.
And, after making such giant strides at the end of last term with effective performances against Albania, Brazil and Estonia, McClaren is eager to ensure the momentum is not lost.
"I would like to name them all even if they don't play," he said.
"I want to clear up the three performances we had in the summer, look at where we are going and what we need to do.
"We have put ourselves into a very good position and I want to get England back on the agenda now, rather than wait for another two weeks."
With Jamie Carragher confirming his international retirement, McClaren may want to take a look at Everton's Joleon Lescott and Newcastle youngster Stephen Taylor, especially as Manchester City's Micah Richards will start at right-back.
Emile Heskey will not be involved as McClaren looks to Peter Crouch, Andrew Johnson, Alan Smith, Darren Bent and Jermain Defoe to fill the void left by Rooney.
As the fourth-highest goalscorer in England history, Owen's ability to find the net is beyond doubt.
However, apart from Crouch, whose 12 goals for his country have largely come against sub-standard opposition, none of McClaren's other choices have proved themselves to be particularly prolific at international level.
Rather than a weakness, McClaren will point to the opportunity about to present itself.
"If I pick them, I believe they can do it," said McClaren.
"Losing Wayne is a big blow because he had done so well in pre-season and was looking really fit.
"But now someone else has an opportunity to come in and prove everyone wrong.
"I feel we have got people who can put the ball in the net. Andrew Johnson can, Peter Crouch has never let us down, Alan Smith is breaking back in, Darren Bent has always been a top goalscorer in the Premier League and Jermain Defoe always scores goals.
"The challenge is there - they have to go out and prove it."