Sunderland are still running as they reach the final stretch of their marathon campaign, but they are definitely feeling the effects of the Premier League.

Still. It's not all doom and gloom. The Black Cats have 48 Premier League points, marking their highest top-flight points haul in 25 years. Not bad going for a newly-promoted side who languished in League One only a few years ago.

However, there's no question that the defence has become leakier, the legs have started dragging, the forwards lack the sureness of those exciting early months.

Regis Le Bris needs to oversee improvements in the summer transfer market, maybe even pushing for an upgrade on the influential Brian Brobbey.

Why Sunderland need to sign a striker

Brobbey has been immense at number nine this season, but the Sunderland striker has emerged as a surprise target for German giants Bayern Munich, and with Nicolas Jackson set to return to Chelsea when his loan spell ends next month, the Dutchman's departure is sadly a possible scenario.

With Wilson Isidor having proved ineffective in the Premier League, a lesser and more uncertain version of Brobbey, it's clear that Sunderland need some variation up top.

Sunderland have been linked with Swansea City striker Zan Vipotnik for a few months now, and as interest mounts in the effective Championship striker, Le Bris will be considering a move ahead of the opening of the market.

Rangers also have a vested interest in the £15m-rated Slovenian striker, so this is absolutely one that Sunderland will need to make a decision on quickly, else they could be forced to look for another powerful and potent striker to take them to the next level in the Premier League.

Why Vipotnik could be a Brobbey upgrade

Vipotnik has been the most prolific goalscorer in the Championship this season. The 24-year-old is attracting plenty of interest in his signature after such an impressive season for the Swans, and Sunderland would be foolish not to pounce.

The forward has scored 26 goals in all competitions this season, and his future is increasingly likely to form one of the central storylines during the summer window, with the Welsh club's head coach,Vitor Matos, remarking that he will only part with the goalscorer for "proper money".

Luckily, Sunderland have some cash in the bank, and they could do with a player of Vipotnik's style, clinical and clever. That combination worked very well in the past when Jermain Defoe was signed, and the Slovenian could now prove the best forward since the retired Englishman.

Having scored 37 goals at the Stadium of Light, retired Englishman Defoe was the barrier between Premier League football and relegation over his 100 appearances, hailed by Sam Allardyce as the outfit's key cog.

Defoe truly was immense on Wearside, and while Brobbey has put in a tremendous shift this term, his return of only six goals from 29 Premier League appearances emphasises the need for a sharper centre-forward.

Whether Vipotnik could be that man is unknown, but the signs are certainly promising for a rising star who has all the attributes to thrive in the Premier League, not only clinical but two-footed, powerful and intelligent when picking his moment.

With the likes of Bayern having shown interest in Brobbey over the past few months, it's clear that Sunderland need to sign a prolific goalscorer this summer.

Could Vipotnik be the man for the job? If he can make the leap from Championship to Premier League football, he might just be the top goalscorer Le Bris needs - their finest since Defoe, perhaps.