Ralph Hasenhuttl says he must face another “lottery” to discover if Southampton can fulfil their Premier League fixture against Brentford.

Southampton secured their place in the fourth round of the FA Cup on Saturday by winning 3-2 away to Sky Bet Championship side Swansea

But victory came at a cost with extra time adding to the heavy workload on a Covid-19 and injury-hit squad and Saints losing full-back Yan Valery to a red card after only half an hour.

Southampton were already without Alex McCarthy, Che Adams, Kyle Walker-Peters, Mohammed Salisu, Moussa Djenepo, Tino Livramento, Thierry Small and Will Smallbone for one reason or another in south Wales, and Hasenhuttl admits his squad is really stretched.

Asked if Saints will have enough players for Tuesday’s rearranged game, boss Hasenhuttl said: “We never know. At the moment it’s all about lottery.

“You wake up in the morning and go to the training ground. You sit at breakfast and you are waiting for new (coronavirus) cases. The problem is with the fixtures coming up. It doesn’t get any easier.

“We have had a long game, overtime. It’s super tough and we have to definitely recover well because a strong team is waiting for us.”

Hasenhuttl was grateful for the five substitutes rule in the FA Cup to provide fresh legs from the bench after Joel Piroe had cancelled out Nathan Redmond’s early strike.

Mohamed Elyounoussi and Shane Long – with his first Saints goal for nearly two years – both scored in extra time after coming off the bench as Brentford were resting several regulars in their 4-1 cup win at League Two Port Vale.

Hasenhuttl said: “When you are one man down for nearly 90 minutes it is not the best preparation for our Brentford game.

“So the biggest laughers are Brentford because they know that we have invested a lot.

“We are in the next round, which is the positive thing, and now we have to recover well.

“We must hope that we don’t have more Covid cases because on a few positions we are running out of players.”

Swansea had not played since December 11 following four postponements, and their cause was not helped by the absence of a crowd because of the Welsh Government’s coronavirus restrictions.

Head coach Russell Martin, who saw his side lead 2-1 briefly in extra time through Jan Bednarek’s own goal, said: “We’ve plotted our own downfall really.

“I feel like we know where we’re at. We haven’t learned anything new.

“We have some outstanding people who are growing every week, we have some players not involved very much and we have some areas where we really need to improve and strengthen.”