It's not often that a player will come on as an 76th minute substitute in the Premier League and manage to score twice before the full time whistle.

But that is exactly what Demba Ba did for Chelsea on Sunday to transform their routine victory over rivals Tottenham into a 4-0 rout. Quickfire strikes in the 88th and 89th minutes added gloss to a triumph that moved Jose Mourinho's side seven points clear at the top of the table.

The Senegalese striker profited handsomely from kamikaze defending from a Spurs side that seemed to have pressed the self destruct button, with the goals moving his tally for the season up to five.

Although that total would seem to be rather meagre, it actually represents a decent return for a player that has only started three matches all season. Ba has been utilised primarily as a substitute by Mourinho in this campaign, making an additional sixteen appearances off the bench thus far.

With Chelsea regularly employing either Samuel Eto'o or Fernando Torres in the lone striker role to accommodate their wealth of creative midfield talent, Ba has found opportunities to impress in the first team very limited this season.

The Senegalese striker is evidently behind his more high profile colleagues in the pecking order, despite the club's well publicised striking issues this season.

In quotes taken from the Official Chelsea website after Sunday's victory, Mourinho described Ba as "very important" and said it is one of the best decisions he has made this season "to keep three strikers."

However, these words cannot disguise the fact that the player is very much on the outskirts of the first team picture at the club. Ba's last start was back in December when he scored the only goal in the Champions League victory over Steaua Bucharest.

Unfortunately for Ba, his time at Chelsea since transferring to the club in January 2013 from Newcastle United acts as a warning for any player that is signed by an "interim" manager.

Rafa Benitez was the man that actually activated the Senegalese striker's well known £7 million release clause. With the Spaniard as manager, Ba featured regularly as he and Torres were frequently rotated in the lone forward role. However, after scoring 13 goals in the first half of the season in a struggling Magpies side, Ba could only muster 6 more in the rest of the campaign.

With Benitez's departure, the Senegalese striker has clearly fallen out of favour with the returning Jose Mourinho. The summer signing of Eto'o has made Ba no more than a fringe player at the club.

Unsurprisingly, there has been frequent speculation over the striker's future. A loan deal to Arsenal was mooted in the summer and there was the potential for a departure in January, only for Mourinho to block it due to Torres' injury.

While his reputation has suffered as a result of his stint at Chelsea, Ba does still boast an impressive record in the Premier League. In 12 league appearances for West Ham, Ba notched an impressive 7 goals in a side that were eventually relegated. On Tyneside, the striker managed a total of 29 goals in just 54 appearances. Although he hasn't been able to show it lately, Ba is a proven goalscorer in the Premier League and would be welcomed at most clubs in the division.

With Torres still ruled out for at least a few more weeks and the fixtures coming thick and fast, the last few months represent a great opportunity for Ba to demonstrate his worth to a manager who has thus far clearly been unimpressed. Have these goals provided the impetus and confidence boost that he clearly needed?

With Romelu Lukaku returning from an impressive loan spell in the summer and heavy speculation that Chelsea are in the market for a new striker, Ba really is in the last-chance saloon. The double against Tottenham was a good start and the forward must prove to everyone that it has kickstarted his Chelsea career.

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