When Manchester United visit Stamford Bridge on Tuesday evening, a duel that may decide the match is the outcome between Chelsea's newest striker Fernando Torres, and Manchester United's hard-nosed central defender Nemanja Vidic.
The two are well acquainted with each other from Torres's time with Liverpool.
Over the years, Torres has gotten the best Vidic, but the tide appears to have shifted recently.
In the first Liverpool-Manchester United meeting last season, the Spaniard scored the first goal of the match at Anfield, in a 2-0 victory.
At one point in that match, Vidic barged in the back of Torres. Later, Vidic brought down Torres and picked up a yellow card in the process. He later brought down Dirk Kuyt and was sent off in the 90th minute.
It was the third straight ejection for Vidic against Liverpool, and his frustration was in clear view.
When Liverpool visited Old Trafford later in the season, Torres struck again. This time, it took him only five minutes. Vidic appeared to be outmatched once more, but at least this time, Manchester United got the win and the defender wasn't red carded.
Vidic appears to have made adjustments this season. In two matches against Liverpool, Torres has failed to score, and the 29-year-old defender has stood his ground while avoiding a yellow card in both matches.
Vidic is among the best central defenders in the world, and has been in great form recently. It would not be surprising if he wins PFA Player of the Year honors.
However, he has made some inexplicable plays over the years. During the World Cup in South Africa, Vidic raising his hand to touch a ball while in the penalty box against Germany was more than just bizarre, it was flat out perplexing.
The three-straight red cards against Liverpool was an unusual trend, as well.
Vidic has refrained from such odd plays this season, so the probability of similar situations unfolding on Tuesday evening are low.
But perhaps Torres was, and still is, in Vidic's head.
The 26-year-old striker, however, has seen a decline in his recent production. He has yet to score for the Blues, and hasn't found the back of the net since January 22, when he scored twice against lowly Woverhampton.
Torres knows the pressure is on to perform for his new club as questions persist about the future of fellow forward Didier Drogba. Aside from Chelsea's big victory over FC Copenhagen, there's not much to be cheerful about when it comes to the Blues' fortunes this season.
Should Chelsea slide in the Premier League standings, many critics will challenge the logic of adding Torres if he continues to struggle to regain his scoring touch.
Chelsea need a win to stay in the hunt for next year's Champions League, and with all of the disappointing stories of the club's current Premier League season, a Torres goal against the Red Devils to get the Blues back on track would be a great start.
A betting person would probably place money on Vidic for Tuesday's duel, though. Torres had his success against Manchester United while with Liverpool, not Chelsea.
Torres is hungry for a goal, but Vidic is playing so well, and likely has a bigger chip on his shoulder when it comes to their rivalry.