AC Milan will move on to the San Siro in a fortnight's time with their tie against Arsenal evenly balanced after an absorbing encounter in London ended goalless.
Arsenal 0-0 AC Milan
Arsenal manager Arsene Wenger had called the first knockout round tie the "ultimate test" for his young side and they proved worthy of the challenge as they pressed the European champions back for long stages.
A faultless display from Zeljko Kalac in the Milan goal, though, kept the English Premier League leaders at bay – even if he was grateful to the woodwork when Emmanuel Adebayor headed against the crossbar from point-blank range in the closing seconds.
Milan's best chance came in a tight first half when Paolo Maldini's header was palmed away by keeper Jens Lehmann.
Carlo Ancelotti's side will now be under pressure to complete the job at home in the return leg on 4 March.
OTHER RESULTS: Celtic 2-3 Barcelona / Fenerbahce 3-2 Sevilla / Lyon 1-1 Manchester United
CHAMPIONS' LEAGUE REVIEW:
[Tuesday 19 Feb] - [Wednesday 20 Feb]