For the second week in a row, Call of Duty: Modern Warfare 2 has taken perch atop Chart Track’s UK Software Sales Chart, fending off valiant advances from newcomers such as Left 4 Dead 2, Assassin’s Creed II and New Super Mario Bros. Wii in the process.

Sales of Modern Warfare 2 this past week dropped a massive 86% from its enormous launch week, which makes this chart topping feat all the more impressive.

Assassin’s Creed II (releasing on Xbox 360, PS3, DS and PSP) debuts at No. 2, outperforming the original entry to the series by 12% on launch week (although the original title notably shot straight to No. 1 in its first week of sales in 2007).

New Super Mario Bros. Wii also makes its first chart appearance, only below Assassin’s Creed II at No. 3, while two other Nintendo titles, Wii Sports Resort (sales down 10%) and Wii Fit Plus (sales up 10%) take positions 4 and 5 respectively (dropping from No. 2 and No. 4 respectively).

Fifa 10 (sales down 5%) drops from No. 3 to No. 6 this week, as Left 4 Dead 2, another debut title in the UK, charts at No. 7. Mario & Sonic at the Olympic Winter Games steps down to No. 8 this week from No. 6, Forza Motorsport 3 falls to No. 9 from No. 5 last week, and LEGO Batman: The Videogame appears at No. 10, moving down from No. 7 last week.

Other interesting movement on the UK Software Sales Chart this week includes the debut of Codemasters’ Formula One racing game, F1 2009 on Wii and PSP at No. 11, the debut of LEGO Indiana Jones 2: The Adventure Continues at No. 16, Dragon Age: Origins slipping down to No. 17 from No. 13 last week and GTA: Episodes From Liberty City falling to No. 21 from No. 10 last week.

Meanwhile, Football Manager 2010 fumbles its way to No. 23 from No. 12, Style Boutique shoots up the chart to No. 25 this week from No. 40, Uncharted 2 trips and falls to No. 29 from No. 18, Tekken 6 drops to No. 33 from No. 20 last week, DJ Hero continues its poor performance by slipping down further to No. 35 from No. 27, and LittleBigPlanet re-enters the chart at No. 38 thanks to the release of the PSP version.

The Top Ten All Format UK Software Sales Chart follows below:

• Call of Duty: Modern Warfare 2 (Activision)
• Assassin’s Creed II (Ubisoft)
• New Super Mario Bros Wii. (Nintendo)
• Wii Sports Resort (Nintendo)
• Wii Fit Plus (Nintendo)
• FIFA 10 (EA)
• Left 4 Dead 2 (Valve)
• Mario & Sonic at the Olympic Winter Games (Nintendo)
• Forza Motorsport 3 (Microsoft)
• LEGO Batman: The Videogame (Warner Bros. Interactive)

Source: Chart Track