Former Indian head coach Ravi Shastri believes the ICC must institute the injury substitution rule in the future to ensure a fair contest at all times in a game. Shastri's remarks came after England seamer Chris Woakes suffered a shoulder injury while attempting to stop a boundary late on Day 1 of the fifth Test against India at the Oval.Similarly, India's Rishabh Pant suffered a fractured toe while batting in the first innings of the previous Test at Manchester. While like-to-like replacements are allowed in the case of a concussion, other injuries do not allow for a substitution.Weighing in on the topic of injury substitutes being allowed in the sport, Shastri told Sky Sports (1:22):"I think eventually they ( ICC) might institute that to take the game forward and have a better contest. You don't want the contest to suddenly drop off. You've to evolve with the times. There's enough debate that can happen on it and a good call can be taken."He added:"But it's a problem for England now. When you look at the bowling today, you would say Atkinson and Woakes were the two best bowlers. There was a lot of inconsistency from the other two. So if Woakes is not there, India will feel if they can get to 250, they will feel they are still very much in this game."Woakes' status and chances of returning for the rest of the crucial fifth Test remain uncertain after he immediately walked off the field holding his shoulder."Positive signs there when someone is ready to scrap it out there" - Ravi Shastri on Sai SudharsanComing to the on-field action, Ravi Shastri was impressed with Sai Sudharsan's willingness to fight under challenging conditions on the opening day of the Oval Test. The 23-year-old battled hard throughout his 108-ball vigil before being dismissed by an unplayable delivery on 38.Playing in only his third Test, Sai has looked the part despite not converting his starts into bigger scores. The southpaw has amassed 129 runs thus far in five innings at an average of 25.80, with a lone half-century."I thought he (Sai) played well and just got a jaffa at the end of it all. There are positive signs there when someone is ready to scrap it out there in conditions where the bowlers have the upper hand. He left well and is tight in defence. He played some beautiful straight drives so positive signs," said Shastri (via the aforementioned source).Sai's weathering of the initial few overs helped India finish Day 1 on a respectable 204/6 in 64 overs.