The midfielder was a doubt for the Champions League first leg showdown at the San Siro after being struck down with a virus. But Lampard has been declared fit to fly out with Chelsea to Italy today.
It is a huge boost for Chelsea, who will be without injured first-team stars Ashley Cole, Michael Essien, Jose Bosingwa and Deco.
Welcome return: Frank Lampard (centre) is back for Chelsea
Chelsea squadCech, Turnbull, Hilario, Ivanovic, Carvalho, Terry, Alex, Bruma, Belletti, Mikel, Ballack, Lampard, J Cole, Malouda, Kakuta, Kalou, Sturridge,Anelka, Borini, Drogba.
Boss Carlo Ancelotti will also have to cope without Cole's replacement Yuri Zhirkov, who did not travel because of a calf problem.
It leaves the Italian facing a headache at left-back given that one possible contender - Paulo Ferreira - was not registered for the Champions League knockout stages.
However, along with Lampard, Chelsea also welcome back defenders Alex and Juliano Belletti who were sidelined with knee injuries.
Meanwhile, Samuel Eto'o has warned Chelsea he is ready to inflict more heartache on them.
Eto'o was part of the Barcelona side that dumped Chelsea out of the semi-finals last season in an incredible second leg at Stamford Bridge. Now at Inter, he is ready to send the Blues crashing out once more.
Raring to go: Samuel Eto'o (right) is out to topple Chelsea
He said: 'My experience against the English was good last season. Now I intend to repeat it against the Blues.
'The boss is relaxed and it's normal that he wants us to show Chelsea our best. You can be sure that every secret of their defensive line has been explained to us. I think it will be a very tactical match that will take the whole 180 minutes over both legs to decide.
'It's necessary to play and prepare as calmly as we can. Anxiety is negative because this is the time to be strong. But I have yet to see Mourinho nervous.'
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