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* Milan reach last 16 after goalless draw
* Only Italian side to reach knockout stage
* Ajax forced into Europa League
ROME, Dec 11 (Reuters) - AC Milan squeezed into the Champions League knockout phase after a battling 0-0 draw with Ajax at the San Siro on Wednesday despite playing for more than an hour with 10 men following Riccardo Montolivo's sending off.
Ajax dominated even before referee Howard Webb enraged the San Siro by showing Montolivo a straight red card in the 22nd minute for a reckless challenge on Christian Poulsen, but Massimiliano Allegri's side held on to secure their place in the last 16.
Despite having a miserable season in Serie A, Milan are Italy's only representative in the last 16 after finishing second in Group H with nine points, a point ahead of Ajax and four behind group winners Barcelona, who beat Celtic 6-1 at the Nou Camp.
"There was a big sigh of relief after that, because it was such an important objective reached for us. It was hard because playing against Ajax with 10 men isn't exactly easy," Allegri told Sky Sport Italia.
"The defence was very well organised but we also managed possession quite well, something we don't always seem to manage in the league," he joked.
Poulsen hit the post for Ajax after five minutes and Milan keeper Christian Abbiati was forced into a number of saves, but the Dutch champions couldn't capitalise on their territorial and numerical advantage and have to content themselves with a place in the Europa League.
"It hurts because it always hurts when you get knocked out, but we played well - we did everything we could bar score," forward Bojan Krkic said.
Frank De Boer's side were, if anything, better when both sides had 11 players, pinning Milan back in their own half with aggressive pressing and slick passing that culminated in Abbiati making a smart save from a powerful Davy Klaassen header in the 19th minute.
Yet their enterprising play stopped almost immediately after Montolivo left the field, perplexed at referee Webb's decision.
"It was a bad foul but there was no malice in it. No one can say Montolivo is a vicious player," Allegri said.
After the red card the game settled into a scrappy affair, in which Milan striker Mario Balotelli led his side from the front with a strong, hard-working performance.
The Milan fans pelted Webb and Poulsen with abuse and the home side came out of their shell, but they struggled to create any goalscoring opportunities.
As the clock ran down Ajax hemmed Milan in their own area with high crosses, and in the final minute of stoppage time Klaassen was presented with an opportunity to snatch qualification, but he could only slice a bicycle kick wide and the San Siro breathed a sigh of relief.
(Reporting by Terry Daley, editing by Stephen Wood)