Great footballers are defined by great feats. Think of Pele's crowning glory in the 1970 World Cup, Diego Maradona driving Argentina to the 1986 World Cup single-handedly (literally in one infamous incident), Johan Cruyff's two goals for Ajax that gave the Dutch masters the middle leg of their European Cup hat-trick in the early 1970s. Or the inspirational captaincy of Franz Beckenbauer and Michel Platini in securing major international glory on home soil for their countries. Or the stunning 7-3 victory over Eintracht Frankfurt engineered by Real Madrid greats Alfredo di Stefano and Ferenc Puskas in the 1960 European Cup final in front of over 130,000 ecstatic fans at Hampden Park in Scotland. Tonight, in Moscow, is Cristiano Ronaldo's golden opportunity to put the stamp of greatness on a stunning season that has seen him top the scoring charts from midfield in both the Premier League (31 goals) and the Champions League (seven goals). As well as the goals, Ronaldo's all-round play has been dazzling, with unstoppable free-kicks, mesmerising stepovers and outrageous flicks and back heels all part of his repertoire. Yet there is still a question mark over his ability to produce his best form on the big occasion. Against tonight's opponents, Chelsea, for instance, Ronaldo has played 12 times and never scored. In all, his record in matches involving England's big four is played 31, scored five. That is a poor return given his soaring goalscoring rate, even taking into account that big-four clashes tend to be low-scoring affairs. The same doubt existed over his effectiveness in the Champions League until this season, and to some extent it still persists. In his first four seasons of Champions League football with United, Ronaldo scored four goals in 32 appearances. The first was in a qualifying round against ordinary Debrecen of Hungary in 2005, then he scored two more when United were already well on top in the 7-1 rout of Roma at Old Trafford last season and finally he made a decisive contribution in a big match with the opener in the semi-final first-leg win over Milan. This season five of his seven Champions League goals came in the group stage against Dynamo Kyiv (three) and his old club Sporting (two) and in the knockout rounds he scored against Lyon and Roma. He has scored five Champions League goals against teams from Europe's big five leagues. Wayne Rooney - outstripped as a goalscorer by Ronaldo numerically - has scored six Champions League goals against teams from the big five leagues in the past two seasons. The defence case for Ronaldo is strong. He is only 23 and, for all his precocious brilliance as a teenage sensation, it took time for Sir Alex Ferguson to get him to focus on hurting opposition defences rather than humbling them with his trickery. Ronaldo's trajectory in the second half of his United career has been amazing. He has scored or made an assist in 64 of his 100 Premier League and Champions League starts since New Year's Eve 2005, when two goals in the 4-1 win over Bolton marked the start of his transformation from wannabe to superstar. United's resurgence as the best team in English football started at around the same time, and there is something of a chicken-and-egg question as to which came first. Was Ronaldo the catalyst for United's revival, or has he merely benefited from playing in a superior team that suits his style? The answer, perhaps, lies in Ronaldo's form for Portugal in Euro 2008 qualifying, where he compiled similar statistics as he has with United. Ronaldo scored eight goals in 13 qualifiers and had 31 shots on target (the most of any player) with a high shooting accuracy of 53 per cent. Now, however, is the time for Ronaldo to prove that he can produce those numbers when it matters most. George Best, another iconic number seven for United, delivered career-defining performances in the European Cup against Real Madrid and Benfica by the age of 22. If that is the company in which Ronaldo wants to be regarded, this is the stage on which he has to perform.