The Champions League returns following the winter break with the first of the knock-out stages. Both Atletico Madrid and AC Milan come into the first leg of their round of 16 tie off domestic victories at the weekend, although there is a difference in recent form between the two sides.

For Atletico, the return of the Champions League could probably not have arrived at much of a worse time. Following a 2-0 loss away to Almeria, the Spanish side’s three point lead at the top of La Liga lasted only a week. To make matters worse, defeats to Real Madrid in each leg of the Copa del Rey sent the cup holders crashing out at the semi-final stage with a 5-0 aggregate defeat.

There are those who consider Diego Simeone’s side as genuine contenders for the Champions League title, and the season’s form until a few weeks ago clearly demonstrated why. Finishing top of their group with five wins out of six meant that Atletico qualified comfortably for the knock-out stages. However, injuries and a lack of strength in depth have recently been exposed, and this could prove to be the Achilles’ heel for Atleti.

By contrast, AC Milan find themselves unbeaten under Clarence Seedorf with the exception of a rather timid 3-1 defeat to Napoli. The Italian side have been climbing up Serie A since the departure of Massimiliano Allegri last month and go into this tie having beaten Bologna 1-0 at the San Siro on Friday night.

Players to watch

Atletico’s excellent form throughout the season has drawn attention from all over Europe, and many are now aware of the capabilities of each player in the team. There is top quality throughout Diego Simeone’s preferred starting XI, from Thibaut Courtois in goal through to Diego Costa firing in the goals up front – four of which have come in the Champions League this season.

However, there are some players who escape underneath the radar. One of these is midfielder Diego Ribas, now back for his second spell at Atletico having signed during the January transfer window. His original spell in the Spanish capital was on loan from Wolfsburg during the 2011-12 season where he scored one of the goals in the 3-0 Europa League final victory over Athletic Bilbao. A fans’ favourite, Diego certainly seems to have slotted straight back into the team with relative ease – no mean feat with Diego Simeone in charge, who is normally quite reluctant to change his starting XI.

Filipe Luis will be a notable absentee as he recovers from an adductor muscle tear. He has formed part of a very settled back five including Courtois in goal and accompanied in defence by Juanfran, Miranda and Diego Godin. From having a back five that has picked itself all season, Simeone has been having a bit of a selection headache in recent matches and doesn’t really seem to have found a solution for replacing the injuries in defence. Javi Manquillo’s recent injury has further added to his defensive selection problems.

The Italian opposition

For AC Milan, this tie marks the beginning of Champions League management for Clarence Seedorf, who is now about a month into his role as manager at the Italian side. Results have picked up since he took over at the club, but the 3-1 defeat to Napoli demonstrates that Milan still have some way to go to compete with the stronger sides in Europe.

It still appears to be work in progress for Seedorf as he gets to grips with which players he wants to use in his formation. Having received the backing of Milan owner Silvio Berlusconi since the defeat by Napoli, the new manager is now likely to be approaching the tie with a certain degree of confidence. There is no doubting Seedorf’s Champions League credentials as a player, but whether or not he can translate that success into his managerial role remains to be seen.

Player-wise, the Italian side contains former Real Madrid players in the form of Kaká and Michael Essien who will be well aware of what Atletico will offer on the pitch. Meanwhile, Mario Balotelli will have the chance to demonstrate his talents to the rest of Europe having scored a quite stunning goal against Bologna on Friday night.

What to expect

Atletico are a team that is quite happy to let the opposition have the majority of possession, but will counter attack with strength – tactics that could work particularly well in the forthcoming away leg. With Atletico showing formidable home form at the Vicente Calderon, the Italian side will be hoping to gain as much of an advantage in their home leg as possible.

Milan’s new manager and Atletico’s dip in form both add to the intrigue of this tie, and it represents an opportunity for both sides to demonstrate to Europe how strong they really are.