The Hoops received the plaudits for their performance in the Camp Nou two weeks ago when they were left devastated by a last-gasp 2-1 defeat.
However, Neil Lennon's side were brought back to earth last Saturday when Kilmarnock defeated them 2-0 at Celtic Park.
That slip up was quickly forgotten when the Hoops put St Johnstone to the sword to reach the semi-final of the League Cup following a 5-0 win on Tuesday.
And while Lennon was delighted with the response of his players Ledley knows they cannot afford to rest on their laurels at Tannadice on Sunday ahead of the Barca clash.
"It's always a good atmosphere at Tannadice and we always get a good game there," the Welsh midfielder said.
"The fans are close to the pitch and while it is always difficult I enjoy it up there.
"We lost there last season so it just shows it's no easy place to go.
"They haven't been doing too well this year so they will be desperate to get some points.
"It's one we are looking forward to as we have to make sure we keep up our recent form.
"We've gone from the Champions League, to the SPL, to the League Cup, and each one is different.
"But we have done this before. We had the same thing last year when we played in the Europa League and we managed to adapt well," added Ledley.
Meanwhile, manager Lennon may ask teenager Tony Watt and Kris Commons to fire Celtic to victory against Dundee United after a spate of injuries to his forwards.
With Gary Hooper suffering a hamstring injury in the win over St Johnstone the Hoops boss is unlikely to risk him at Tannadice before the Barcelona clash.
Georgios Samaras is a doubt with a ankle injury while Lassad Nouioui is out with a thigh injury and Anthony Stokes is unlikely to feature before December.
But Lennon has every confidence Commons and Watt are finding the target often enough to ensure the goals don't dry up at Tannadice.
The Hoops boss said: "Tony takes the ball in really well. He has got good feet and his touch is getting better.
"He still needs to work on his awareness, but I think that will all come with the more experience he gets.
"Considering the players we have out, and the role he has played, Tony has been a huge bonus for us.
"I don't know how many Kris has got already this season. He must be near double figures. So there is no reason why he can't go 15 to 20.
"I am not setting him any targets. I just want him to keep playing," added Lennon.
On Saturday, Hibernian came from behind to defeat 10-man St Mirren and move top of the league, while Inverness Caledonian Thistle moved up to third with a 2-1 win away to ten-man Kilmarnock.
Aberdeen's 10-match unbeaten run in the SPL came to an end at Victoria Park as Ross County claimed a 2-1 win over the Dons.
Motherwell ended a four match losing streak as they defeated St Johnstone 3-1 at McDiarmid Park.
Bottom club Dundee posted only their second league victory of the season in a tight encounter at Dens Park against Hearts, 1-0.
Sunday:
Dundee United v Celtic (1245)
Source: AFP
Source: AFP