The Champions League returns tomorrow, and this is one of the games to watch out for on matchday 1.AS Roma welcome Atletico Madrid to the Stadio Olimpico in their opening fixture of this season’s Champions League, in what promises to be a testy encounter.In the two previous times both teams have faced each other in the competition, the Spanish side have come out winners, but it will be hard to call this one seeing as it is still a new season and neither side has really set their respective leagues alight so far.Match FactRoma have won just two Champions League group games (5-1 vs CSKA Moskva on 17 September 2014 and 3-2 vs Bayer 04 Leverkusen on 4 November 2015) in the past six years. In that time, Atlético have reached the final twice.Previous meetings• Atlético won both of the teams' only previous fixtures, posting 2-1 victories home and away in the 1998/99 UEFA Cup quarter-finals. José Mari (13) and Roberto (46) scored for Atlético in the home first leg, with a Luigi Di Biagio away goal (75) giving Roma hope for the return.• The hosts were level on aggregate 32 minutes into the Stadio Olimpico return through Marco Delvecchio, but Juan Carlos Aguilera levelled on the night on the hour and Roberto's second goal of the tie (88) gave the Spanish club another 2-1 victory and a 4-2 aggregate success.Match backgroundRoma• Second in Serie A in 2016/17, Roma are in the group stage for a tenth time and the third in four years. • The Italian side were beaten by FC Porto in last season's play-offs (1-1 away, 0-3 home). They got as far as the UEFA Europa League round of 16, where they were defeated 5-4 over two games by Olympique Lyonnais.• That Porto reverse means Roma have won just one of their last seven home games in the UEFA Champions League – qualifying included – losing four.• Roma are also without a win in six UEFA Champions League matches, home and away and including qualifying, since a 3-2 home victory over Bayer 04 Leverkusen on 4 November 2015. That is their only success in their last 15 games in the competition.• The Serie A team's last encounter with Spanish opposition ended in a 1-0 home defeat by Villarreal CF in last season's UEFA Europa League round of 32 second leg – although Roma went through, having prevailed 4-0 in Spain.• Roma's overall record against Spanish clubs is W10 D4 L14; at home it reads W6 D1 L7. They are without a win in three home fixtures with Liga sides at the Stadio Olimpico, since a 2-1 scalp of Real Madrid in the 2007/08 round of 16.Atlético• Third in Spain in 2016/17, Atlético only missed out on becoming the seventh team to win all six matches in a UEFA Champions League group when they went down 1-0 at FC Bayern München on matchday six last season.• Diego Simeone's men went on to reach the semi-finals, but a 3-0 first-leg reversal at Real Madrid proved too much to retrieve despite a 2-1 second-leg success in the last European game to be played at the Vicente Calderón.• Atlético won two of their three away fixtures in last year's group stage, but have managed just three victories in their last nine UEFA Champions League away matches (D2 L4).• Atlético are unbeaten in their last three trips to Italy, most recently a 0-0 draw at Juventus on matchday six in 2014/15. Their record away to Italian clubs is W4 D2 L4; overall it is W13 D3 L7.