Alonso had the opportunity to halve Barcelona's lead with a shot on goal, but chose to go to the ground instead, angling for a spot-kick. However, the referee did not award a penalty despite Chelsea's appeals and Olivier Giroud was even cautioned for his overzealous protests.
Antonio Conte was seen gesturing wildly too, clearly furious with the decision, arguing after the match: " [I have not seen] it on TV but during the game from the bench, for me it was a clear penalty.''
In an post-match interview with 'BT Sport', Frank Lampard and Rio Ferdinand disagreed and said they thought that the official's decision was the right call.
''At first glance it looked a penalty but when you really analyse it I don't think there is quite enough. The slightest touch and he was on his way down," Lampard argued.
Although the former Chelsea midfielder conceded that could have been different if it had been the other way round: ''Messi might have got it, that's the way these games go unfortunately but there isn't enough in it there for me.''
Ferdinand echoed his former West Ham team-mate's opinion, adding: ''I don't think it was a penalty myself, I thought he was looking for it and went down too easily. I don't think there is enough, he is looking for it and is trying to fool the ref there a bit and I think the ref doesn't take to it.''
Barcelona triumphed 4-1 on aggregate to progress to the Champions League quarter-finals alongside Bayern Munich, Juventus, Liverpool, Manchester City, Real Madrid, Roma and Sevilla.