Rio Ferdinand and Wayne Rooney gave Untied a flying start with Cristiano Ronaldo adding a brace as the Old Trafford outfit completed their biggest European away success in nine years.

Victory in the re-match, on home soil in a fortnight, will seal a spot in the last 16 with two games to spare.

And on this evidence, there is little to stop it happening,.

"Our forward play at the moment is excellent," said Ferguson, whose side have now scored 12 times in their last three games.

"Some of our movement was excellent and although the finishes were easy, you have to be there to take them.

"To score four goals away from home in Europe represents a good performance at any time and we could even have had more.

"With people like Rooney, Ronaldo, Carlos Tevez and Ryan Giggs we have great ammunition.

"We have nine points now and that puts us in a very strong position."

United's win was achieved without key midfielder Paul Scholes and Patrice Evra, who suffered a calf strain during the warm-up.

Scholes will have a scan on a knee injury suffered in training yesterday when he returns to Manchester and with Owen Hargreaves and Michael Carrick already out injured, Ferguson will hope the damage is not too serious, even if his stand-in Darren Fletcher produced an effective display on his first start of the campaign.

"We do have strength in depth, " said Ferguson.

"But the more important factor is that the changes are not affecting our performance.

"John O'Shea had to switch to left-back when Patrice pulled out and Darren obviously came into midfield.

"Both of them were excellent.

"Of course, those two players have been here for a long time and understand what playing for this club means.

"But others, like Carlos, Anderson and Nani have joined us this summer and adapted really quickly."

After Ferdinand had nodded home his second in as many games, Rooney finished off a close-range effort to provide himself with the perfect 22nd birthday present for tomorrow.

Although Diogo Rincon and Ismael Bangoura found the net for Dynamo, with Ronaldo slotting home twice in the middle of those two strikes, the result was never in doubt.

Aside from the Carling Cup defeat to Coventry, United have now won 10 games on the trot, and appear to be hitting form at just the right time.

"Dynamo probably caught us at the wrong time," said Ferguson.

"Our form is strong now, much stronger than it was in our previous matches in this competition."

Ferguson also confirmed veteran keeper Edwin Van der Sar had not suffered an injury and his decision to introduce Tomasz Kuszczak 10 minutes from the end had been pre-planned.

"Edwin wasn't hurt," said Ferguson.

"It was in my mind to bring Tomasz on even though we conceded the second. I was not going to change it."