BLACKBURN Rovers' UEFA Cup opponents CSKA Sofia will fly into England tomorrow confident they can pull off a shock in Thursday's first round first leg at Ewood.

The Bulgarians are currently flying high after five straight wins have catapulted them to the top of their domestic league.

But what is of more immediate concern to Graeme Souness and his playing staff is the fact that the most successful side in the history of Bulgarian football also boast an enviable record in European competition.

Facing a team of Rovers' calibre will certainly hold no fears for manager Stoycho Mladenov and his cosmopolitan squad.

Since their formation back in 1948, CSKA have met English clubs on five previous occasions in Europe.

And during that period, they have twice reached the semi-finals of the European Cup, on top of a last four appearance in the Cup Winners' Cup.

Nottingham Forest and Liverpool are among an impressive list of scalps which also includes European giants such as Juventus, Parma and Monaco.

And Souness knows from past experience that Rovers risk the embarrassment of an early exit if they take their challenge too lightly.

"This is not going to be an easy tie for us," said Souness, who played against CSKA on a couple of separate occasions in the early 1980s.

"Bulgarian teams have some experience of playing in Europe from the past and they are usually decent sides.

"So we'll give them the respect they deserve because they can't be mugs if they've qualified for the UEFA Cup in the first place."

CSKA first came up against English opposition back in 1970 when they lost 2-0 on aggregate to Chelsea in the now defunct Cup Winners' Cup.

However, they gained suitable revenge for that defeat a decade later when they eliminated Brian Clough's Nottingham Forest over two legs in the European Cup.

A year on a Graeme Souness-inspired Liverpool then dumped them out of the same competition after the current Rovers chief grabbed a stunning hat-trick in a 5-1 quarter-final victory.

But the following season, the Bulgarians got their own back by pulling off arguably the biggest result in their history when they slayed the Anfield giants on their way to a place in the last four.

Since then, however, they have struggled to re-live those glory days of the early Eighties despite being able to call on players like Hristo Stoichov, aside from a semi-final appearance in the Cup Winners' Cup in 1989.

On the last occasion they met English opposition in 1999, they were overpowered by Bobby Robson's Newcastle who triumphed 4-2 on aggregate after a 2-0 win in Sofia.

Domestically, though, they remain one of the most formidable forces in Eastern Europe having won the Bulgarian title a record 28 times and the Bulgarian Cup an equally impressive 22 times.

During the last two seasons, they have lived in the shadow of arch-rivals Levski Sofia.

But under the guidance of Stoycho Mladenov, who was the Bulgarian national coach until recently, they appear equipped to regain their domestic crown.

Of the current squad, Portuguese midfielder Joao Paulo Brito would appear to stand out as the ace in the pack.

But striker MacDonald Mukasi was part of the South African squad who competed in the World Cup finals recently.

And Mladenov also rates homegrown players such as Svetoslav Petrov, Todor Yanchev and Emil Gargorov.

As an unseeded team, they booked their place in the UEFA Cup first round by virtue of a 5-1 aggregate win over Belarus outfit Dinamo Minsk.

And they will certainly go into Thursday's game in good heart after last week's thumping 5-0 win over Dobrudzha strengthened their grip at the top of the table.