Brazil star Willian has been assured that matches against Argentina and Australia will be properly monitored following tragic attacks in Manchester and London, and Monday night's deadly siege in Melbourne.

Those incidents have raised alert levels around the world and the Chelsea attacking-midfielder admitted he was concerned about another attack during their upcoming games against Argentina and the Socceroos.

“I’m a little bit worried," he told reporters after being asked about the danger.

"But the players have to think about the game. There are people responsible to take care of our safety and we have to be prepared for the game and not think about that.”

Willian training at Lakeside Stadium, Melbourne

However Victoria Police denied there was anything for the public to fear and assured the MCG would be monitored closely.

But they warned there may be delays for fans entering the ground at Friday night’s sell-out clash between Brazil and Argentina as a result of the increased security presence.

“Victoria Police has increased its security overlay for the upcoming international soccer matches to be played at the MCG to ensure that there is a highly visible police presence at the venue, as well as in the vicinity and surrounds of the venue,”  said a spokesman.

“This presence will include the use of specialist police resources. Police will be liaising with the teams’ private security in addition to security at the MCG.

“Fans can expect to be searched using metal detectors along with physical inspections of all bags. Given this, it will take some time to get everyone through the gates, so we’d encourage the public to be patient and factor that time into their planning for the event.”