Dundee United manager Mixu Paatelainen insists the departure of John Souttar will have no impact on his squad.

The 19-year-old defender joined Hearts moments before Monday's transfer deadline and Paatelainen had not added to his squad in the latter stages of the window.

The Finn had previously expressed optimism that Souttar would extend his contract beyond the summer but United cashed in after several bids from their Ladbrokes Premiership rivals despite their predicament, 11 points adrift at the foot of the table.

Paatelainen said: "John obviously was an important player in our squad and featured regularly.

"But we are well covered for that position, the central midfield position and other positions John played. So it doesn't affect us at all. We are as strong as before."

Paatelainen has signed six players since taking over in October - Eiji Kawashima, Gavin Gunning, Guy Demel, Florent Sinama-Pongolle, Riku Riski and Kyle Knoyle - although fitness issues have limited their collective impact.

"I'm happy with the squad," he said. "We have good balance in the team and good cover for every position.

"Of course people are saying we never made a deadline-day signing but who says we are finished?

"We are constantly looking to improve the squad and making sure that, if there are players available that would improve us, then we would look to strengthen. It never stops. We are always looking and contemplating options."

Paatelainen's options are reduced for Saturday's William Hill Scottish Cup tie with Partick Thistle.

"We have quite a few flu victims, quite a few players missing training this week," said the former United striker, who also has Riski and Callum Morris out through injury.

"There are all sorts of illnesses. So we have to wait and see who is fit and who is not. We won't be 100 per cent when it comes to the size of the squad."

United remain in a huge battle to avoid relegation but Paatelainen is determined to mount a cup run.

"The Scottish Cup is a fantastic tournament," he said. "We are looking forward to playing our part and hopefully progress.

"It won't be easy because Partick are a good team, pass the ball well and have good players.

"But the cup is very important to us and we want to do well."

United reached the fifth round thanks to Blair Spittal's perfectly-placed free-kick at Airdrie, which was almost identical to his goal in a Dundee derby defeat seven days earlier.

And the midfielder hopes to get another chance to show his dead-ball skills against Thistle.

"There were a couple of us who used to stay out every day after training with Luis (Zwick) the goalkeeper and practise," Spittal said.

"I had never scored one in a game until the Dundee game. I put that one down to luck and then the week after against Airdrie I got another one in pretty much the same place.

"To be fair there are a few of the boys that are always in the running for free-kicks, like Scott Fraser, and hopefully if we get one on Saturday then we can take the opportunity."

Spittal also netted twice against Kilmarnock in United's most recent game, form that saw him linked with a January move to Hull.

The 20-year-old said: "They are obviously a big club. It was flattering at the time but I don't think there was any concrete interest so I was just concentrating on playing for Dundee United."