The Brazilian arrived at Stamford Bridge on loan until the end of the season from Corinthians on Friday and has been handed the famous number 11 shirt by the Blues.
Pato has been training at Cobham in recent days as he works on his fitness and missed the 5-1 FA Cup win over MK Dons on Sunday afternoon.
Speaking at his pre-match news conference on Tuesday afternoon, Hiddink refused to rule out the possibility of Pato making his first appearance in a Chelsea shirt at Vicarage Road.
Chelsea tweeted via their official Twitter account on Tuesday afternoon:
Guus Hiddink says Pato has not had many training sessions and a late decision will be made on his availability. #CFC
— Chelsea FC (@ChelseaFC) February 2, 2016
Chelsea head into Wednesday’s game in 13th place in the Premier League table and looking to build on their impressive 1-0 win at Arsenal last month.
The Blues then host Manchester United at Stamford Bridge on Sunday afternoon.
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